The 18-year-old, who has moved to Old Trafford from Crewe, has been challenged by his manager to prove himself in training ahead of the new season and earn a place in midfield.
"At Crewe, it was one camera and one person," he joked, "at United, it's the whole world.
"At Carrington, even with the building work around it, it is a complete change from Crewe. I thought Crewe's facilities were respectable but, to see this, it's a completely different world for me."
But Powell agrees with boss Sir Alex Ferguson that he still has a lot to learn.
He said: "I've still got a lot to develop, I'm not near my best yet."
"I'm hoping to achieve what people expect me to achieve.
"I want to show I am a Manchester United player and show what I can do."
