Ringworm is a fungal skin infection that classically appears as a round or oval patch with a raised, scaly, slightly redder border and a clearer centre, giving a ring-like look. It tends to be itchy and can slowly enlarge, and it is contagious through skin contact, shared towels or pets.
Eczema patches are usually more diffuse and poorly defined, very itchy, dry or weepy, and often appear in the skin creases or where you have had eczema before. The distinction matters because the treatments are different: fungal infections need antifungal treatment, whereas a steroid cream alone can actually make a fungal infection spread.
If you are unsure, see a pharmacist or doctor before treating. A clinician can examine the skin and sometimes take a quick scraping to confirm the cause. Seek review if the rash spreads, does not improve with the chosen treatment, becomes painful, or shows signs of bacterial infection such as weeping and crusting. This is general information only.