If you are comparing whole months, they are probably about equal.
November has the Food & Wine Festival the first half of the month. A lot of people, especially locals, come to Epcot, for this. Also, Jersey Week is in November - New Jersey schools have a week off and it seems the entire state migrates to WDW. That's usually right around the Super Soap Weekend too at MGM.
Thanksgiving week is getting busier and busier, but still not as mobbed as Xmas week.
We were in WDW Nov 15-19 - after F&W, but before Thanksgiving and it was VERY low crowds.
Now, December, the first 2 weeks are low crowds and then it starts to pick up and by the time you hit Dec 19-20, then it starts to get heavy. Xmas thru NYE is busiest week of the whole year.
So, to sum up, November is probably more manageable if you avoid Thanksgiving (Weds - Sat) and Jersey Week. December is most managable if you can travel before Dec 20.