Question

What is the difference between amino group and amine?

Answer 1

It is basically a matter of convention, and whether you're talking about a class of compound or the functionality within a compound.

Explanation:

An amine is basically an ammonia derivative where one or more hydrogen atoms has been replaced by an organic substituent (alkylic or aromatic group).

When an amine is considered as the functional group of a molecule, it is referred to as an "amino group".

So you would say that $C{H}_{3}C{H}_{2}N{H}_2$ is an amine (ethylamine), but you would say that the functional group in ethylamine is an "amino group".