What is the difference between a graft and follicle hair transplant?

Single follicle is a single hair string or a single hair shaft . But in our scalp anatomy , hair exist in form of small groups as a family which contains 1,2,3, or 4 to 5 hair follicles. During harvesting of hair we try to isolate a part or whole of this small hair family/bunch and harvested part is called as graft. 

In the human, hairs grow in groups of 1-4 hairs each called Follicular Units.  in 1997, I published the seminal article on follicular unit transplants (see web reference below) which I taught the art of using exclusively follicular units for hair transplants. That means that one follicular unit can have from 1-4 hairs each and these follicular units should only be used when transplanting people as this technique produces the most natural results as my article taught.