500 Days of Duolingo: What You Can (and Can’t) Learn from a Language App

While they’re similar in concept, they differ a lot in the specifics:

Duolingo offers a skill tree of lessons that use listening exercises, flashcards, and multiple choice questions to drill you on new words, phrases, and sentences. Memrise offers similar lessons to Duolingo, introducing new words and phrases with flashcards, listening exercises, and more. While it uses similar multiple choice or listening exercises as the others, it uses conversational examples to demonstrate how to use new words or phrases when speaking with another person.

Source: www.nytimes.com