For offense, Carolina runs the ball very well and scores a lot of points. But are 24th in passing and 11th in total yardage, there are much better offenses in the league. The defense isn't in the top 5 in any category other than turnover margin and rushing yards allowed, they allow 322 yards a game despite being on the field the second least amount of time.
In comparison Denver's defense, is 1st in yards allowed, 1st in passing yards per game, 3rd in rushing yards allowed per game, and 4th in points allowed per game. Despite being on the field much longer then Carolina's defense is.
Carolina is the much more well rounded team being good on both sides of the ball, but they aren't elite at either. Take one side of the ball away, and Carolina is a .500 club. The offense and defense are not good enough to win games on their own. Denver's defense has proven to be good enough to win despite having a below average offense all year. To me that is the main difference between being good or being elite on one side of the ball.