Девочка vs. девушка
This course uses девочка as the normal word for girl and translates девушка as girlfriend. It usually, though not always, accepts девушка as a translation for girl. I'd learned девушка as the normal word, and that's what I've mostly heard from Russians. The word I'd learned for girlfriend is подруга, though I've seen девушка used with that meaning as well. What's the difference in meaning between these words, if there is any, and why does Duolingo use девочка instead of девушка? Could a native speaker help me out?
I'm going to make a guess. Девушка means a girl or a young woman, девочка implies a younger girl. They picked девочка as being a closer parallel to мальчик. Подруга is the word for girlfriend, but Russian speakers, just like English speakers, will sometimes say девушка instead of подруга just as an English speaker might sometimes talk about his girl instead of his girlfriend. Is that right?