Answer
Amines are organic compounds that contain nitrogen atoms with a lone pair. Basically, they are derived from ammonia (NH3) in which one or more hydrogen atoms are replaced by an alkyl or aryl group, and so they are known as alkylamines and arylamines respectively. The functional group of amine is R-NH2
Amidines are related to amides by replacing the C(O) group in the formula of an amide with C(NH), hence the functional group of amidines is R-C(NH)NH2.
The diagram below is the general formula for primary, secondary, and tertiary amines: