Question :Which is better to say «Я учу русский» или «Я изучаю русский»?

3年前

Is it better to say «Я учу русский» or «Я изучаю русский»? I'm always confused about which verb to use. Учить or изучать.
From what I learned in uni: «Учить» is for small things "like words, rules, and poems" and «изучать» is for larger subjects "mathematics and languages", but sometimes I see
«Я учу русский язык». Is one sound more authentic than the other?