Happy Birthday, Boots And Mittens!

Question #1: Can you believe these two are four years old already?

Question #2: Can you guess who is who? (The answer is below the break.)

Here's a recap of cat-related posts:

Boots And Mittens
Kat Birthday

Wait, there are only two? And this one makes three? Sheesh, I'm going to have to start writing more posts about my cats. Anyway, happy birthday, you guys!

That's Boots in the first picture, and his sister Mittens in the second. The family resemblance is uncanny.