One of these kids is not like the other

I loved that song on Sesame Street when I was little!

I took this picture with a smile on my face, but I think the question is unfair.

Is the freak different kid, Mac because he is still wearing his Halloween costume (best $1 at the thrift store I ever spent) or Capps because he is holding on to Summer?
When I took this picture it was 45 degrees outside and the kids were playing "bad guys" outside. To make this picture better I should have had all the kids line up in their coats and hats, with Capps mixed in.