Stroboscopic photography is research.

(1) As can be seen from the figure, A moves along the same straight line. If the distance of A is equal in the same time interval, A moves at a constant speed along the straight line.

(2) As can be seen from the figure, B moves along the same straight line, and the distance of B becomes larger and larger in the equal time interval, but if the distance is not equal in the equal time, B moves along the variable speed straight line.

Therefore, the answer is: uniform linear motion; Variable speed linear motion; Compare the distances traveled in the same time.