Some yeast roll recipes call for eggs and some don't. What is the difference in the finished product?

Yeasted dough recipes which include eggs usually call for butter as well. The combination of eggs and butter turns the dough a beautiful golden color. Too, the lipids (fats) in the yolks and the butter (obviously) have a nicely tenderizing effect on the dough, as fats cause protein (gluten) strands to pull apart in places. All of which are perfect in a lovely dinner roll.

I find the egg yeast rolls to have a richer flavor and a firmer texture.