How do I tell the difference between eczema vs folliculitis vs dermatitis?

Hi! I’m not sure how eczema looks like. I have something red and itchy on my hand. Please, can somebody explain to me what eczema is? My friend thinks that I have folliculitis. I also don’t know what it is. How do I tell the difference between eczema vs folliculitis vs dermatitis? Thanks!

Folliculitis usually appears around tiny pockets from which each hair grows. It looks like small, white-headed pimples. Folliculitis often clears by itself in a few days. Dermatitis or eczema is a general term that describes an inflammation of the skin. It can occur in many forms, it usually involves swollen, reddened and itchy skin. Eczema need to be treated.