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.
Round(random(0.5,100.5)
Floor(random(1,101)
Int(random(1,101)
Floor(random(100))+1
Int(random (100))+1
Are all equivalent, use whatever whatever you like.
Ceil(random(100)
Is also basically the same thing, except you have a negligible chance of actually getting 0. And since I'm being needlessly pedantic now, I believe JavaScript uses a 53 bit float, so the actual chance world be around 1 in 90 quadrillion or so.
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.