Please advise what is the difference between eczema and psoriasis?

Very similar! Eczema-dry cracking psoriasis. The same hla genes are identical for both. My belief is that they are variants of the same immune process, although many might disagree! i treat them the same way!
Different. Eczema or atopic dermatitis is due to a defect in skin barrier function causing water loss-> itching-> rash. Multiple gene mutations are linked to impaired skin barrier -> allergic sensitization. Psoriasis is caused by overproduction of skin cells and is also genetically determined. The rash is not usually itchy and the condition may affect nails and joints. The treatments are totally different.