Boy howdy is there a difference!
I primarily collect 19th century only and I currently have 5 treadles from 1890 and earlier (Singer, Wheeler & Wilson #8 & #12, Willcox & Gibbs, Howe) and three just the heads (White, New Home, and another Singer)
They sew very differently. The Wheeler & Wilson 8 is the smoothest running of mine, followed by the Singer, then the Willcox and Gibbs (which is the smoothest stitching), the Howe really shows that it was one of the earliest designs. My daughter says it sounds like a train...
EVERY one of them had thread in the treadle mechanisms. Even the ones that ran smooth and I thought were clear.
Once you remove the foreign crud, grease it, and adjust the slack they run really nice.
Another point is that there is even a difference in operation between two of the same machine. I have two of the W&W #8's and they sew differently even using the same treadle base. I believe this is due to the handcraft nature and constant mid model "improvements" that they went through during this development era.