He is grey = His hair is already entirely grey. He's going grey=His hair has some grey in it, but isn't fully grey yet. Eventually, he'll be totally grey, but not yet.

You would not normally say, “He is grey.” “He is going grey” means that his hair is turning grey over time.

Hello, He's grey - the hair on his head is totally grey (white) He's going grey - his hair has strands of grey ( he's not totally grey, but overtime, he'll be totally grey) Regards

He is grey , is very unclear and not a statement that would be used in English. He is going grey is correct and just means his hair is getting white because he is getting old . The first sentence is unclear because the situation is unclear , grey is most commonly used for grey hair, When people get old. Or grey can sometimes be used to describe people to show how boring they are. Example “little grey men in suits

hey Lin, you mean he was sick and he was about to die and he turned grey? :) Because he had choked on something? More info will help..