What is the difference between a concept and a definition?

A concept is a label (a Word or a phrase) that captures the essence possessed by a class of objects. It is an abstracted essence of a class of objects that is shared by all the members of the class.

A definition expatiates the abstracted essence in terms of the genus the objects belong to and specifying the principle or element that differentiates the given class of objects (the species) from the genus.

The concept of man, for example, refers to the essence that is common to all human beings amidst the great many individual differences that humans posses.

A definition of the concept of man (e.g., "Man is a rational animal") elaborates the concept by identifying the genus (animal) and specifying rationality as the differentiating element.

-MJ Arul.