How can i tell the difference between eczema and ring worm?

Growth, center, size: Both are often round and have scale, but typically ringworm grows outward, with central clearing. Also, eczema is typically very itchy, whereas ringworm is generally not unless it gets infected...

Sometimes it's hard: Ringworm (see picture), which is a fungal skin infection, is usually round or oval and has raised pink edges with central flattening and scaling. It can enlarge and may or may not itch. Eczema comes in various shapes, including round or oval, but tends to be a solid patch of itchy, dry, raised, rough, red rash. Sometimes a test (skin scraping) is needed to see if fungus is present.