Question

explain what distinguishes first class levers from second and third class levers.

Explanation:

First - class levers have the fulcrum between the effort and the load. Second - class levers have the load between the effort and the fulcrum, and third - class levers have the effort between the load and the fulcrum. This difference in the relative positions of the fulcrum, effort, and load distinguishes them.

Answer:

The relative positions of the fulcrum, effort, and load.