@literally45-- Eczema is identified by patches, whereas psoriasis is identified by scales.
Both eczema and psoriasis have to do with the immune system. Dry skin can be a symptom of both of these conditions but it's always accompanied by other symptoms. Itchy, dry skin by itself is usually caused by environmental factors like climate.
Psoriasis doesn't cause blisters as far as I know, it causes areas of dry scaly skin. Eczema causes very red inflamed, flaky skin with or without blisters. Skin with eczema is usually red, but skin with psoriasis can also have a red, or white appearance.