The manual for the BD55 is also the same manual for the BD35. I do not see anything in there that indicates different video parts -- but that does not necessarily mean that they are identical. Some avsforum member will have to compare the two side by side to figure out the differences, if any.
According to the manual, the BD55 uses 21 watts, and the BD35 uses 20 watts. The BD55 is also spec'ed at being 1/4 inch taller. They are both listed with the same weight.