What is the difference between a meter and a square meter?

Square meters is a measure of area and linear meters is a measure of length or distance.
A metre is a measure of length only. EX: It is one meter from the wall to my desk chair. A square metre is a measure of area. EX: The closet floor is one square metre. It consists of four sides, one metre each--the back of the closet + 2 sides + the front of the closet where the door is. The area enclosed by this is one square metre.