What cuts are "stir fry beef" and "stewing beef"?
They are not equivalent cuts and 'should not' be used interchangeably.


Stir Fry meat is cut from the more tender cuts of beef (tri-tip, sirloin, rib-eye) and don't require much time cooking to be 'ready to eat'.
Stew Beef is from less tender cuts (the Chuck or Eye of Round) which will become tender after a 'significant' time braising (cooking in liquid).


That said...the food police won't show up at your door if decide to interchange these, and using stir fry beef for stew isn't a terrible thing to do...but you will likely not be happy if you try to switch the other way.