You are listing brands. Are Goodyear tires the same size as Firestone?
There are two common sizes for skate bearings. You can use either size in any skate as long as you have wheels and spacers designed for the same size.
The most common is 608, which is used in the vast majority of recreational, fitness, agressive, and some hockey skates. Places that sell them frequently don't list a size because almost everyone uses them. They are about 7/8" in diameter.
Some hockey wheels are designed for 688 bearings which are much smaller (about 5/8" diameter).
If you look at the pictures on these links, you will notice that the 688 bearing has a much shorter side profile than the 608
688 - www.rollerbob.com/partpics/med.688ZD.jpg
608 - www.rollerbob.com/partpics/med.ZD7.jpg
12+ years of skating.