And you'd be right in that thinking Brenden.
I think you may be trying to generalize it to much. Zooanthids are also of the class Anthozoa and are sometimes called colonial anemones. My yellow polyps behave exactly like an anemone in it's feeding behavior. The distinction comes in when you move farther down the table.
Zoo polyps/button polyps: Class- Anthozoa; subclass- Hexacorallia; order= Zoanthidae
mushrooms: class- Anthozoa; order- Corallimorpharia
anemone: class- Anthozoa; order- Actiniaria
I'm gonna quote something for you cause, well, this is just easier than me trying to explain. This is an quote from Fenner's book.
Withing the Phylum Cnidaria, anemones are placed in the Class Anthozoa, which are single or colonial polyps with the medusoid stage completely missing. This group includes the bulk of cnidarian species (6,000+) encompassing corals, sea fans, and sea pansies.....
Sea anemones are separated from other anthozoans in the subclass Zoantharia and the Order Actiniaria. They are often called the "true anemones."
Not sure this is what you wanted or if I've just confused you more. I guess the easiest way for me to explain it is, just because they are of the same class, they are completely different animals and though some are simular, they have different needs and care levels. So, to say a mushroom is an anemone is correct, but you can't compare care levels with true anemones. Hope this helps.