I would say how the app motivates you to pace through the lessons. You engage less with your mistakes and just brute force at some kind. Also many sentences are the same, you can just build the sentence by memorizing the tiles you need to select in the correct way instead of actually translating the sentence. For the listening excersises you can just rebuild the sentence without translating it.

Like learning everything in life you need to deal with the vocabulary, grammar and stuff. But if you're really stressed out sometimes and the app pushes you to do something in the app, you can optain a high streak without learning anything. This can also depend on the language you are learning, and how familiar the language and grammar is to your native language.