What is the difference between a square number and a perfect square?

Yes, they are the constant thing. When tribe make known that 36 is a precise just (for example), they limited that its square root is an integer (6). Every plenty is a square, but it is only a 'perfect square' on the occasion that its just root is an integer. For example, 2 is a square, passing over it is not a 'perfect square' because its square root is the irrational number 1.4142 ...