回复：thanks again, but I am a little bit confused

High gloss polyurethane is a harder finish but it will not hide scratches, nicks and scrapes. Any unevenness or flaws left in the wood after it is stripped and sanded will be glaringly magnified after the full gloss polyurethane finish dries. Scratches and scrapes that happen after the polyurethane dries are also more obvious on full gloss than semigloss.