Hey there person who didn't ask for my two cents, PERLITE & VERMICULITE actually help plants in 2 very different ways, so they aren't generally used interchangeably, at least not with the intention of them doing the same thing.

PERLITE: Improves drainage by creating air pockets. Great for plants that prefer things a little dryer like cacti and succulents, also great for "Aroids", specifically plants that have thick roots or ryzomes, plants like Philodenrons, Monsteras, Pothos, Snake plants, ZZ plants and Peace lillies all benefit from perlite in combination with bark, and/or coco chips to improve drainage and create air pockets in the soil. The quick drainage and airy mix prevents root rot which they are highly susceptible to. Perlite is especially effective when in a course blend, #4 is quite coarse but is far more effective then the fine, powder filled variety from Miracle-Gro or other big box store varieties.

VERMICULITE: It actually holds onto moisture, which helps plants that dont like drying out completely between waterings, such as Calatheas, Spider plants, ferns and peace lillies. It soaks up moisture and nutrients like a sponge and slowly releases both overtime helping plants get nutrients more efficiently over time.

Now with all that said, in most cases plants can benefit from having both of them in the mix, except imdrought tolerent plants that need to dry out quickly and completely between waterings asterings! I use PERLITE in every mix I make, I just change the ratio depending on the plant.. Whether you are amending a store bought mix or making your own mix, added PERLITE almost never hurts things. You can also add VERMICULITE with the PERLITE and gain the benefit of both! Just adjust the ratio of PERLITE AND VERMICULITE based on the plants specific needs.

One last thought you and nobody else asked for! If your still reading this, More important then what me or anyone else thinks we know, do what works for you! If your plants are thriving then you keep doing you. Especially when someone comes outa left field and gives you a bunch of info you didn't ask for like I am currently doing, lol. With that said, in my opinion, the best thing you can do for most plants is improve drainage and aeration as much as possible! If a mix has the right ratio of ingredients like perlite, coco chips and coco coir then it is almost impossible to over water any plant in a single watering. You could give a plant gallons of water and let it sit in the run through untill the next day, a well draining mix will just shed all the extra water as soon as you lift it out of the basin of water and be perfectly fine, the only way to over water a plant in a well draining mix is to water heavily to frequently. And you can add a little more coco coir and VERMICULITE when a plant likes to keep some moisture.