It varies a bit!
Here's a photo. The 25mm figures are the plate-armoured RAFM warrior second from the left, the Ral Partha shield maiden third from the right, and the RAFM half-orc on the far right. The rest are 1/72 (MiniArt Burgundian, Zvezda hoplite, Strelets bashi-bazouk, Emhar Viking).
To my eye, the Ral Partha figure works pretty well with most of the 1/72 stuff. The RAFM figures are more cartoony, with big, characterful heads. But the shield maiden would look fine with a group of the Emhar Vikings - especially if you afford her just a little bit of 'hierarchical scale' as a character figure.
Oddly, though, the 25mm figures look fine with each other.