Lego Question 1

The question is: what is the difference between all of these pieces.

First off the longer pieces can hold together more pieces. The difference between the grey and black pieces are that the black ones have a lot more friction so it won't rotate as much as the grey piece. Its the same with the blue and beige pieces, the blue one has more friction than the beige.

This red piece can connect a cross piece to a circular hole, but it can't act as a axle because of friction.