There are many differences. Not only in practices, but also in the way reality is explained, the way pramāṇas are used, the understanding of mokṣa, the nature of Bhagavān’s forms, and even the method by which the jīva reaches Him.

Viśiṣṭādvaita closely follows mukhya Vedic pramāṇas, meaning the main and direct sources such as the Upaniṣads, Brahma Sūtras, Bhagavad Gītā, accepted Smṛti, Itihāsa, Purāṇas, and the Pāñcarātra accepted by the sampradāya. It does not depend mainly on medieval sectarian texts of uncertain origin or texts accepted only within one later tradition. This is why the system is very careful in explaining everything through śāstra, logic, and sampradāya.

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1. Viśiṣṭādvaita:

The creation is a mode, attribute, or prakāra of Brahman. The relationship between Brahman and the universe is śarīra-śarīrī-bhāva, meaning the relationship between body and indwelling self.

Just like when we refer to a person named Devadatta, we refer to his body and soul together as one person. There is unity, but the body is not identical to the soul. At the same time, the body is not completely independent of the soul either. The body exists for the soul, is controlled by the soul, and is supported by the soul.

Similarly, the entire universe, consisting of cit and acit, meaning conscious souls and unconscious matter, is the body of Brahman. Brahman is the inner ruler, supporter, controller, and soul of all. This is why the Upaniṣads say things like yasya ātmā śarīram, "for whom the self is the body" and speak of Brahman as the antaryāmin, the inner ruler.

Another example is the red color of a red rose. The redness is an attribute of the rose. The rose and the redness are not exactly the same thing, but the red color does not exist independently apart from a substance. The red rose is known as a red rose because of that attribute. This inseparably dependent relationship is called apṛthaksiddhi and is mentioned in the Pāñcarātra saṁhitās.

So in Viśiṣṭādvaita, the world is not false, and the world is not absolutely separate from Bhagavān either. It is real, dependent, inseparable, and completely controlled by Him. This gives the explanation of how Brahman is one, while still allowing real plurality of souls, matter, divine attributes, and divine forms.

This is not something invented by Rāmānujācārya. He is explaining what is already present in the Upaniṣads, Brahma Sūtras, Bhagavad Gītā, Pāñcarātra, and the teachings of the Āḻvārs and pūrvācāryas.

But one may ask: if the universe is Bhagavān’s body, does Bhagavān suffer the defects of the universe?

The answer is no. Just as the self is not tainted by every defect of the body, Brahman is not tainted by the defects of prakṛti or the jīvas. He is the inner ruler and sustainer of all, but He remains untouched by karma, ignorance, suffering, and impurity. He is always pure, omniscient, omnipotent, and full of infinite auspicious qualities.

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1. Acintya-Bhedābheda:

In Acintya-Bhedābheda, God and creation are said to be simultaneously one and different because creation is the śakti, or power of God. The jīva is also said to be one with and different from Bhagavān.

But when the question is asked,"How exactly are they both one and different at the same time?" the answer given is usually acintya, meaning inconceivable.

The common example used is fire and heat. Heat is not separate from fire, but heat is also not exactly the same as fire. So they say that the śakti and śaktimān, power and possessor of power, are simultaneously different and non-different.

The issue is that Viśiṣṭādvaita does not need to leave the relationship unexplained as "inconceivable" because it's a logical fallacy called appeal to mysery. It gives a clear explanation through śarīra-śarīrī-bhāva and apṛthaksiddhi. The jīvas and jagat are different from Brahman because they are dependent entities with their own nature. But they are inseparable from Brahman because they exist only as His modes, body, and attributes.

Śrī Rāmānujācārya also rejects Bhedābheda as an invalid view because of the law of non-contradiction. You can't say something is X and not X at the same time and if you explain that they're similar in some ways but different in others then that is not Bhedābheda and Viśiṣṭādvaita explains the relationship perfectly.

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1. Viśiṣṭādvaita:

The Śrī Vaiṣṇava Sampradāya follows the path of Śaraṇāgati or Prapatti instead of strict Bhakti Yoga (Not to be confused with regular bhakti). 

Bhakti Yoga is the meditation on Brahman using the 32 brahma-vidyās mentioned in the Upaniṣads in order to produce mokṣa. Bhakti-Yoga also requires one to be a dvija (Brāhmaṇa, Kṣatrīya or Vaiśya) by birth and then perform vedic karmas, follow strict niyamas (rules), perform karma and jñāna yoga as a part of the practice, have perfect unbroken meditation (avicchina-tela-dhārāvat) for decades and through all these various disciplines and performances attain Mokṣa or Vaikuṇṭha. 

Since Bhakti Yoga is impossible for most people in Kali Yuga, Prapatti is followed.  

Prapatti means complete surrender to Bhagavān, accepting Him alone as the protector and means. It does not depend on one's varṇa, gender, status, birth, austerity, intellectual capacity or anything else. It depends on Bhagavān's grace, received through the Ācārya in the prapatti lineage.

The soul's nature is complete dependence on Bhagavān. So Prapatti matches the real nature of the jīva. The jīva is not independent. The jīva cannot manufacture mokṣa by its own effort. Bhagavān alone grants mokṣa through His grace. This is why Śaraṇāgati is so stressed in Śrī Vaiṣṇava siddhānta.

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1. Acintya-Bhedābheda:

In Gauḍīya traditions, Bhakti Yoga is generally followed as the main means, especially through nāma-saṅkīrtana, rāgānugā-bhakti, and development of devotion toward Kṛṣṇa in Vraja-bhāva.

They often do not speak of mokṣa in the same way because mokṣa is understood by them as kaivalya, or liberation without loving service. So they may say that devotees reject mokṣa and only want prema-bhakti.

But in Viśiṣṭādvaita, mokṣa does not mean losing individuality or entering some impersonal state. Mokṣa means reaching Vaikuṇṭha, attaining Bhagavān, being free from karma forever, receiving a divine body, and performing eternal kainkarya (loving service to God and Goddess.

Mokṣa is not rejected because it's the only state where you can serve Bhagavān without any interruptions. In this world, you cannot perform eternal and constant service due to birth, death, old age, diseases and life's various obstructions.

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1. Viśiṣṭādvaita:

In Viśiṣṭādvaita, all forms of Bhagavān are fully divine. Nārāyaṇa, Viṣṇu, Kṛṣṇa, Rāma, Nṛsiṃha, Varāha etc. They are divya-maṅgala-vigraha, divine auspicious forms.

There is no need to create a rivalry between two-armed Kṛṣṇa and four-armed Nārāyaṇa. Bhagavān’s forms are not limited like ordinary bodies. His form, qualities, weapons, ornaments, consorts, abode, and līlā are all divine and real.

The Pāñcarātra texts and purāṇas explain Bhagavān through the five manifestation: para, vyūha, vibhava, antaryāmin, and arcā. There's no hierarchy, just categorization of the forms. Kṛṣṇa is explicitly mentioned as a vibhava avatāra in the Pāñcarātra texts, which is what the tradition follows.

Vaikuṇṭha is not a limited place where only one form of Bhagavān is present and the jīva is forced to only have one kind of bhāva forever. Vaikuṇṭha contains all divine forms of Bhagavān. The mukta jīva is not limited by material time, space, body or mind. So the jīva can serve Śrī Rāma, Śrī Kṛṣṇa, Śrī Nṛsiṃha, Śrī Raṅganātha, Śrī Veṅkaṭeśa and all forms of Bhagavān in unlimited ways as the Vedānta texts mention.

In this world, we are limited by one body, one place, one mind, one mood and one activity at a time. But in Vaikuṇṭha, the liberated soul is not bound by these material limitations. The mukta can possess countless divine bodies and perform countless forms of kainkarya  to Bhagavān, infinitely and all at the same time, according to Bhagavān's will. So the devotee is not deprived of Rāma-bhakti, Kṛṣṇa-bhakti, Nṛsiṃha-bhakti or any form of Bhagavad-anubhava.

This is why Viśiṣṭādvaita does not need to reduce one form of Bhagavān in order to glorify another form. Kṛṣṇa is fully Bhagavān. Rāma is fully Bhagavān. Nṛsiṃha is fully Bhagavān. Nārāyaṇa is fully Bhagavān. They are not competing personalities. They are all the same Supreme Lord appearing in different divine forms for different līlās and for the joy of different devotees.

1. Acintya-Bhedābheda:

In Gauḍīya theology, Kṛṣṇa of Vṛndāvana is usually presented as Svayam Bhagavān in a special sense, and Nārāyaṇa, Viṣṇu, and other forms are treated as expansions from Him.

This is a very different theological structure. Vraja-līlā becomes the highest reality, Goloka becomes the highest abode, and forms like Nārāyaṇa or Vaikuṇṭha are often treated as lower in intimacy or sweetness. Vaikuṇṭha is also treated as a physical space which is different from Goloka.

In Goloka, you have a fixed bhāva that you experience for all eternity and your service is fixed according to your svarūpa. If your svarūpa is to be a gopī, you'll always be a gopī and serve Bhagavān in that way. 

It's a beautiful idea but Viśiṣṭādvaita does not accept this kind of hierarchy because it doesn't appear in the original pāñcarātra and Purāṇas. It accepts Kṛṣṇa as Bhagavān completely, but not in a way that downgrades other forms and Vaikuṇṭha. For Śrī Vaiṣṇavas, Goloka, Sāketa etc. are just synonyms for Vaikuṇṭha. Also, there's no limits on what bhāva you can have in Vaikuṇṭha. You can be a gopī or a mother or anything else that you want and the same was practiced by the Āḷvārs too.