How well can cats tell the difference between stuffed and real cats?

Do they ever have to do a double take. Do they even notice them or do they just look like a pillow to them?

I had 3-4 cats once (lost track... yrs ago) and one day brought home a bright blue stuffed panther about 2' tall, 3' long. One cat ignored it. One cat ran. The third cat (male) attacked it! Who knew?

Well I have some pretty realistic rabbits that some of the cats have done double takes.

Charlie likes to "kill" them. He has a few that he drags down the steps and plays with.

Perhaps because my cats are all indoor/outdoor, they aren't fooled at all. It takes only one sniff and the stuffed toy will be treated as either a toy, litterbox (yes, it's peed on sometimes) or totally ignored.

I've never had the cats pay any attention to a stuffed animal. Maybe because they've always had various ones around. But Perky, my dog, when we are out walking and happen to go by a yard with a statue in it.. she will stop in her tracks, and start into her deep threatening bark, sometimes her fur even stands on end.. it's SO funny, especially because she doesn't react like that to, say, a REAL dog. But she sees a statue of a Rottweiler puppy today, and she keeps turning back to tell it off until we can't see it anymore, then walks calmly past a yapping terrier tied into a yard. Silly thing.