Honestly, I can barely tell my dogs apart. We've started putting Toad in a tee or sweater to help people distinguish between the two. It doesn't hurt that Toad just wears clothes really well (every time I look at him in a sweater, I think, damn, this dog was made for clothing!). As a budding cartoonist, I should be able to find the differences and illustrate them. It's a great exercise - when cartooning two identical little puffy white dogs, nearly the same size and shape, how can I make them distinctive to someone who is quickly reading a comic? I did some "studies" in my sketchbook - thought I nailed it, then showed Eric, who knows the dogs better than anyone.
"Can you tell which is which?" I asked
"Yes, obviously! The top one is Toady, and the bottom one's Pete."
It was actually the reverse. Oh well. Back to the drawing board...