Dandelion vs. Cat's Ear
Hypochaeris radicata
The difference between Cat's Ear and Dandelion leaves:
The stems of Cat's Ear are not hollow, they are wiry and will usually have more than one flower on each stem.
The young leaves, root, flowers, and buds of Cat's ear are edible similar to dandelion with comparable nutritional benefits, but that's where the similarities stop.
It is not used the same medicinally. I did bump into a very interesting research paper regarding the root extract. Here were the results:
Basically, they found enough positive evidence to warrant continued research into the root for use as an antibacterial (although they will be looking for the active constituents in order to make a patentable medicine). We, on the other hand, can use this information as holistic herbalists and appreciate that the research has been done.
Here's a link to the paper if you'd like to read it in its entirety.