девочка vs девушка
I have a question concerning the difference between девочка and девушка.
In the Duolingo course it is very clear, Девочка means girl in general, while девушка is girlfriend. However, I just looked up both words in the dictionary, and both are just translated as "girl" or "little girl". The meaning "girlfriend" is not mentioned.
(As a German I tend to use the trusted leo.org dictionary: https://dict.leo.org/russisch-deutsch/m%C3%A4dchen)
Is there any Russian how can explain the difference between the two words? Thanks in advance!