United's flying Dutchman has scored 10 goals in his last 10 games for the league leaders, who travel to face Spurs at White Hart Lane on Sunday.
Villas-Boas reckons the scintillating form Van Persie has carried over to United from his final season at Arsenal sets him out as a great striker.
"For them he has been a tremendous success and it has been a transfer with immediate impact and immediate results," he said.
"He is a player who last year impressed and his level of form was incredible. To make a move to an even bigger club and arrive the way he has and triumph there is something outstanding - he is probably the difference at this time between the Manchester clubs.
"I think what is exciting with Van Persie at this stage is the fact that you know he was transferred to Manchester United after last year's amazing goal scoring record, and he kept on scoring.
"It didn't affect him and his form. He continues to be the amazing talent that he is."
The 29-year-old Van Persie has now scored 23 goals in all competitions for the Red Devils, but his manager Sir Alex Ferguson has refuted claims United are now a one-man team.
England striker Wayne Rooney has struggled to match Van Persie's form so far this season, but returned from injury in the FA Cup replay win over West Ham in midweek. And Villas-Boas believes he can be equally as devastating.
"He sacrifices himself for the team and embraces all of that United team spirit and desire to win," he said. "I think he has overcome some difficult moments in his career but he is a top quality footballer."