Green hair algae, also known as GHA, is a long strand of fuzzy algae that grows on the glass or rocks of the aquarium. GHA can grow quickly and starve out corals.
Green turf algae is a dense algae that looks very similar to Green Hair Algae. Green Turf Algae grows directly on the rock and is very difficult to remove.
reefstable.com
Here's a link to look at photos of common algae and how to get rid of them.