As I understand the different types of yeast, instant yeast and bread machine yeast are the same, and have ascorbic acid (Vitamin C) added to further speed up the action of the yeasts and to strengthen the dough (by preventing the gluten bonds from breaking down). So-called "RapidRise" yeasts, such as sold by Fleischmann's, for example, is a different strain of yeast altogether from the other yeasts mentioned above. They work much faster, by about 50 percent (basically eliminating one of the rise times), but their cells also die faster, making them less desirable for doughs, such as pizza doughs, that may be subjected to long periods of fermentation. Like instant yeast, RapidRise yeast requires no hydration and can thus be combined with the other dry ingredients. RapidRise yeast also contains ascorbic acid. Active dry yeast does not contain ascorbic acid.
The lines are getting blurrier all the time as yeast producers modify their yeasts. For example, some active dry yeasts that normally call for hydration (like the SAF Active Dry Yeast) can be mixed in with half of the flour and other dry ingredients, and it can also be used in bread machines. The RapidRise yeast can also be used in bread machines.