The easiest way to get a good handle on what may unfold on Sunday is to take a look at a quick overview of the Jaguars and the Browns statistics to this point in the season (best stat per category highlighted in team color):
As you see above, both teams are very comparable in nearly every category. Even their net points are identical. The Browns claim most advantages in the offensive category as well as the claim to being the NFL's number one pass defense. The Jaguars are one of the best all-around defenses in the league.
My prediction is that the Jaguars win this game 17-7. The Browns' one weak spot on defense is their rush defense, which is one of the worst in the league. While the Jaguars' offense as a whole is pretty poor, they do run the ball very well. That's the mismatch that the Jaguars need to exploit, and I think that's the difference in the game.