I think PRC movies seem to look a little better; also, their films often had original scores(not the greatest, usually by Erdody. But at least a bit more distinctive than the stock library "bogeyman" music used by Monogram).

Often, the sets from both studios seemed interchangable. And THE DEVIL BAT seems like a Monogram, mainly because it uses the same musical cues that were so prevalent in the nine films Lugosi did for that studio.