Grub
This kitten was just borned and doesn't know anything except drinky milk. It needs to be fed and stimulated to go to the bathroom every 2 hours.
Bumper-car Kitten
About 2 weeks old
This kitten is learning to walk and see out of its newly opened, kitten-blue eyes. Its tail sticks straight up as it toddles around, like the pole on the back of a bumper car. It needs to be fed and stimulated to go to the bathroom every 3-4 hours.
Yep, that's a Kitten
About 5 weeks old
The kitten comes online. It is now aware that it exists. It's about the time for it to start eating something other than milk, and learn to use the litter box.
Lanky Kitten
This kitten looks like a smaller adult cat, but there's something distinctly young about it.
Kitty
The majority of a cat's life is spent as an adult cat. It is a capable predator, and sleeps for most of the day.
Old Kitty
There's no particular age where this happens, but you will know when a cat has become an Old Kitty. It usually has greasy or clumpy fur, and is either going blind or deaf. It may need a ramp to get onto the couch or bed. Its favorite thing is probably to be warm.