They both mean "drink". However personally I don't think its a good app, the course is really unorganized

I've been finding Doulingo helpful with other Japanese learning material. I say resourceful if are a very busy person like myself but it doesnt explain a lot of things. Also, some of the Japanese spoken in the app is kind of hard to hear as well as not always native to how native speakers would usually say. But, its free so its prettu useful.

I've occasionally experienced something similar (with other languages as well) but for the most part, I've found duolingo rather successful. I'm by no means fluent and I'm only just beginning but it's working for me so far.