The Frenchman believes the two coaches have very different styles and revealed he is ready to fight for his place after making his comeback from injury.
The Italian replaced outgoing boss Mourinho during the summer, with the Portuguese returning to the Premier League with Chelsea after three years in charge at Santiago Bernabeu.
Varane emerged as a crucial part of Mourinho's plans during the latter months of his spell in Spain, but he stresses he has a good relationship with new boss Ancelotti, despite his different style on the training pitch.
"You can't compare Mou with Carlo, they have very different styles," he was quoted as saying by Marca. "But I get on very well with the new coach."
Varane played his first game in five months in midweek against Copenhagen in the Champions League, and the Frenchman admits it has been an arduous process of recovery following surgery on his knee.
"I think it's been a very delicate operation, changing my stance and the way I run. That's why I've had to be careful and take my time," he continued. "It's been quite a lengthy injury and it's a pleasure to return and experience the good feeling of being on the pitch.
"I'm not at 100 percent yet because I've only had one game. It's been hard. At 20 years old I'm eager to play and to watch from the sidelines isn't easy. But I'm back, I'm happy and I'm ready to fight for my place. My knee has responded well and I've had no problems."
Varane was also included in the France squad to face Finland in this month's crucial World Cup qualifier, and the 20-year-old says he is thrilled to have been included in Didier Deschamps' plans.
"I'm proud to represent my country. I'm ready to return for France. The coach is in contact with all the players and we have a normal relationship."