The left-back has heaped praise on the winger after his performance on Saturday night but says he still has some way to go to be mentioned in the same breath as the Portuguese star
Los Blancos stormed to victory on Saturday night, after Bale opened the scoring with a header on 33 minutes, before Karim Benzema made it 2-0 three minutes later.
The world's most expensive player added two more goals in the second half with his right and left foot to complete the perfect hat-trick and leave onlookers comparing him with team-mate Ronaldo - who missed out through injury.
And Marcelo told reporters: "You cannot compare Bale and Ronaldo. Cristiano is above the rest of the players and everyone on the team knows that. Bale is a great player, though, and he is on the right track."
The victory has closed the gap between third-placed Madrid and top two Barcelona and Atletico Madrid to three points, with the Blaugrana set to face Athletic Bilbao on Sunday night.
But despite the comfortable nature of the victory, Marcelo targeted further improvements after the game.
"Every game is difficult and Valladolid did not allow us to play at first. But then we got well set defensively and offensively," the 25-year-old added.
"Our first goal is always to win the game - whether we play well or badly. But we also have to put a show on for the fans and in recent games I think we have improved a lot. We kept a clean sheet as well and that is important for us."