Portugal icon Luis Figo played with the two during a glittering career that saw spells with the national side as well as Real Madrid and Barcelona.
The 45-year-old was giving the impossible task of distinguishing who the better player was, however Figo, who is currently the adviser of management to UEFA, sided with his Real Madrid team-mate Ronaldo Nazário.
"It depends, CR7 scores more with his head, but both are impressive," he told 'DAZN'.
"As long as Cristiano Ronaldo hasn't stopped playing, I'll say that Ronaldo (Nazário) was number one in front of goal, but they're both players who guarantee you goals.
"The important thing is to put them in the position to score, then they do the rest."
Brazilian Ronaldo scored 62 goals in 98 games for Brazil, including two goals in the 2002 World Cup final win over Germany.
After retiring in 2011, Ronaldo recently purchased a 51% stake in La Liga club Valladolid for around £27million, becoming their majority shareholder in the process.