Not sure if it really matters, but the mag wells in the frame are different, possibly affecting the feel of the grips. The P229 mags are wider at the bottom and taper in about 2/3's of the way up while the P226 mags have straight sides. That is why P226 mags will fit in a P229 and stick out of the bottom, but P229 mags will not fit into a P226, besides being a little short.
To me the grip of the P229 feels fatter and the P226 feels longer front to back, but that may just be me. I prefer the feel of the P226, but I actually own both. My P226 is an older model in 9mm while my P229 is in .40, and I personally believe that you won't find a better gun for shooting .40 than the P229.
I am assuming you are talking new guns, but if you were talking used and 9mm, the older (pre-98?) P226s had carbon steel slides while the P229 and newer P226s have stainless steel slides. I won't get into differences there because that usually turns into a religious war.