Learn vs. Study
The verb study describes an activity, the activity that you undertake when you want to learn about something.
In contrast, the verb learn focuses on the moment when something has become part of your knowledge.
The verb learn also contains a sense of completion and permanency; usually, when you have learned something, you know everything about it and you don't easily forget it.
The sentence below sounds because of the sense of completion implied by learn. If you have truly learned something, that is, if it has become part of your knowledge, you are normally able to use that knowledge.
Strange:
- I learned German last year, but I can't speak it.
It's possible to study something without learning it, however, so the sentences below sound fine.
Natural:
- I studied German for three years, but I can't speak it.
- I studied very hard, but I didn't learn much.
Studying is an activity that we do over a period of time, but learning is a change in our consciousness rather than an activity. Consider the examples below:
Strange:
- I learned German for three years.
Natural:
- I studied German for three years until I finally learned to speak it.
Because learn implies a sense of completion, it is not usually when we are talking about subjects that are vast and that no one can learn everything about. Instead, we use it with more limited fields of study.
Strange:
- I learned science.
- I learned philosophy.
- I learned music.
Natural:
- I learned how to play the piano.
It's hard to imagine that someone could learn everything about science. However, you can study science or learn about science.
Learn about is similar to learn in that what you learn about becomes part of your memory, but learn about does not have the sense of completion that learn does, so it sounds more natural in the sentences below.
Natural:
- I'm studying history.
- I'm learning about Japanese history.
- I want to learn about Western philosophy someday.