The Welsh veteran believes that Rooney's unselfish attitude and willingness to create goals for his team-mates has hallmarks of the overwhelming influence that Ronaldo had on the first-team during his time at Old Trafford.
Sir Alex Ferguson recently criticised the England international striker for his lack of goals compared to summer signing Robin van Persie, but two goals in last weekend's 3-2 derby victory over Manchester City took Rooney's total to four in his last two Premier League games.
"Wayne is the kind of player who can score goals, but if someone is scoring more he's not too bothered," explained Giggs. "He's quite happy setting goals up and pitching in with important goals like he did on Sunday.
"It's like when Cristiano was here, he scored a lot of goals. It's similar with Wayne, he's not just an out and out goalscorer. He's more than that.
"He's the catalyst to everything good that we do. He can score goals, make goals. It's a massive plus for him to get the goals at City."
And, while Rooney continues to impress Giggs, the 39-year-old is only too aware of the impact that £24million man Van Persie has made since arriving from Arsenal in August, adding that the Dutchman could make all the difference in Manchester United's bid to reclaim the title.
"He's one that we are glad to have," he added. "He's not surprised me because I knew that, at 29, he was a ready-made, experienced world-class player.
"He just has that bit of class that can make a difference – like it did on Sunday and in other games. You see it in training, you see it in games, he's just a brilliant player."