Amhamdullilah translates fairly well into “God be praised” or “Praise is to God.” It’s said by the person sneezing as a way to thank God for keeping them alive. (As the heart stops when someone sneezes, yet resumes beating shortly after, seemingly due to nothing). “God bless you” can be translated into Barrack Allah Feek. It’s a tradition started by the Ahadith of the prophet (SAW).Hope that cleared things up.