Oops! Sry, wrote the answer in comments. Учиться is like just "studying" - the process of learning. But for example, if you are doing some researches in something, you can say "Я изучаю". Заниматься is just an action of doing something. If you are tidying your room, for example, you can say "Я занимаюсь уборкой" as well. It's like "I am doing the cleaning of my room", something like that :D So "заниматься" you can use with any action, not only studying. However "учиться" can be used only when you are learning something. "Учиться рисовать"(learn to draw), "Учиться ходить"(learn to walk), "Учиться играть на пианино"(learn to play the piano) etc.