Recently bought a pack each of Napoleonic french, a command set from warlord and a pack of officers from Perry miniatures.
Originally scoured the web for my own purposes and found nothing so bought a pack of each and have taken comparison pictures of both alternating between warlord games and Perry miniatures.
As can be seen the difference in height/proportion is minimal with warlord being 'heroic' scale to Perry's more anatomically accurate offerings I was expecting stark differences but even up close it takes some effort to see with warlord being slightly taller/chunkier than perry.
Normally i'm very ocd about these things due to my autism but i'd happily mix them even in skirmish games.
Apologies for the photos being spread out, had taken them with my iphone which leaves the file size quite big, hope this has been helpful!