Oh, Welsummers ARE a "rare" enough breed. Don't feel bad about that! And they lay the most lovely really dark, terra cotta colored eggs!!!! I have one.
Check out this handy, dandy Chicken Breed Chart. It's very useful. You'll notice Welsummer "rarity" quotient is 12%.
Welsummer chicks have very defined, dark Vs on their heads. (See the photos in Luke's post.) The EEs I've seen did not have that in their "chipmunky" looks.