The Ecuador winger joined United from Wigan in a £16million deal this summer, while Ronaldo left for Real in a £80million deal.
Whelan said: “Antonio will never be a Cristiano Ronaldo. They are completely different players.
“He’s gone from playing in front of 18,000 to playing in front of 70-odd thousand but I’m sure he’s going to do well.
“I always knew Alex Ferguson wanted him. He came to see me last year and was very upfront about it. That’s what I like about him – he doesn’t creep around your back.”
Whelan added: “United didn’t play well at Burnley and were iffy against Birmingham.
“They haven’t lost two in a row for a long time and we’ll be up for it, don’t worry.”
