Former United captain Neville played alongside the Portuguese ace for six seasons before Ronaldo's record-breaking £80m transfer to Real in 2009.
Neville is aware Ronaldo remains one of the best in the world at exploiting weak defenders, and feels that he deserves to be in the "same bracket" as Lionel Messi, Pele and Maradona.
"Ronaldo is a bully," said Neville. "He bullies the weakest defender. He does it all the time. He did it to Manchester City against Maicon. He will play on the left wing. If he can't get on the ball he will play centre-forward, midfield, right wing.
"He changed my perception at United. We had a midfield four - Beckham, Keane, Scholes, Giggs - I played with Beckham for seven years. They never had the freedom to decide their position on the pitch.
"Suddenly I didn't have someone in front of me who would come back and double up on the left-winger. In those early years he used to go wandering off. He was told to play on the right by Sir Alex Ferguson and would end up on the left. That was unheard of.
"He just decided his own position, which was based upon where the space was and who was the weak link. He made me realise you didn't always need to be in your shape.
"We had a player who was beyond a level of talent I had ever seen. He would go and win us game after game. I suppose that is more important.
"Now, he is a monster. I saw him on Saturday evening. He picks the ball up in an innocuous position, 30 yards out, does some type of shimmy I can't even describe let alone do, beats a man and whacks it in from 25 yards.
"You can't defend against that. He is in the same bracket as Messi and you can put them both up there with Pele and Maradona."