What is the difference between green tea and green tea powder?

I am making a mask and I don't have powder, but I do have green tea.


so is there a really big difference?What is the difference between green tea and green tea powder?
Yeah, I think this is it, not sure though.


But, I had a recipe for a cake that had green tea powder in it. And I think, not sure, that it's dehydrated green tea or something.