What crazy said!
The physical distinctions between zooanthids and palythoas will lend themselves to be easier seen as you've spent more time trolling the forums.
Zooanthids tend to be more colorful (opinion, but not absolute) with varying patterns. They will tend to form a mat, covering an area of rock like it were grass, whereas palys tend to generate polyps apart from each other and grow to be much larger. Palys get to be pretty big and will catch meaty foods which land in their polyps! It's cool to watch during feeding time. They make an excellent accent to the lower rocks, reaching up from the sand bed to the light.
Palythoas still come in very striking colors, radiant green, electric blues, and so on. Be wary, though, of the substance called "palytoxin." Some palys carry more of this neurotoxin than others, but most of the ones you see will be fine.
Whether you choose to go with zoos, palys, or BOTH, you'll be in for a real treat as far as color and presentation are concerned.