Int does removes the decimals. It effectively rounds towards 0.
Floor rounds towards negative infinity.
Ceil rounds towards positive infinity.
Random gives you any number from the lower bound up to but not including the upper bound.
Are all equivalent, use whatever whatever you like.
int(random(1,100)) can never result in a 100 though, while round(random(0.5,100.49)) has a 1% less chance to get 100 compared to 1-99, and round(random(1,100)) would have half the chance of getting 1 or 100 compared to the other numbers.