Μελετώ = study. Μπορεί να μαθαίνεις μελετώντας αλλά τα δύο ρήματα δεν έχουν την ίδια σημασία.
I agree, it has a different meaning but people often say " I want to study English" meaning I want to learn English. After all you can't study a language without learning it and you can't learn it without studying it! :-)