Hmmm I don't know... But where I live, there are TONS of stray cats. Eko sees them all the time on walks, and he is aggressive toward them. He is aggressive towards my cat, he has actually grabbed my cat out of the air with his mouth and slammed him to the ground when my kitty tried to jump on the table to get to his food bowl. So he REALLY doesn't like cats. But the first day we got Xena, she was the size of a cat and Eko didn't attack her. He's never attacked any puppies we've seen when we are out and about even when there are stray cats around, so he seems to know the difference.
I don't know if that answers your question, just sharing my experience