Other differences are, that on the Pietta Remy, the loading lever latch located on the underside of the barrel, is just lightly silver soldered in place in a hole and on some occasions I've read about, has become loose and fallen out. So if someone has both the Uberti and the Pietta, and they want conversion cylinders, they will have to buy two separate conversion cylinders that are specially made to fit each manufacturer's brand.
But I have heard some people saying the Uberti conversion cylinder WOULD fit into the Pietta. Also some times the cylinder pin is different so they sometimes won't fit anyway. Because that makes the barrel to cylinder gap much too wide. You can fit an Uberti Remy conversion cylinder into a Pietta Remy, but you shouldn't. Also, this means that a conversion cylinder for a Pietta Remy is too long and will not fit into an Uberti Remy. The Pietta Remy has a slightly longer cylinder so it will hold a tad more powder than the Uberti Remy. But in my looking at both the Pietta and Uberti stainless 1858 Remys, I've found a few differences between the two that might be of interest to some here that may be unaware of those differences. At first glance the Pietta and Uberti 5.5 inch barrel, stainless Remys look identical.
I looked at both Uberti and Pietta stainless 1858 Remy versions. 44 caliber stainless, 1858 Pietta Remy gem pictured at the bottom here about a week ago.