No real difference barring increased damage and the wow powerleveling recommendation for a second offtank on heroic. The achievement Make Quick Werk of Him is usually tougher on 10-man due to the inability to stack raids buffs on the level of a 25-man raid. 36,111 raid-wide DPS is required to kill him on heroic; on normal, you'll need 12,000.
Trash between Patchwerk and Grobbulus is all run-of-the-mill Flesh Giants with the exception of the so-called Frogger Hallway. A continuously-spawning series of oozes will path across the hall directly in front of you and will usually one-shot any player who gets too close. You'll need to move between the three lines of oozes without hitting any, which is actually a little harder than it sounds given player or server latency. The technique that works for me is to err on the side of going too close to the ooze to your right; this will compensate a bit for any latency on your end, and I've never died doing that. Of course, the true cynic would opine that a foolproof strategy is waiting for someone in front of you to die, then crossing while there's a gap in the oozes, but theoretically you can't count on this to happen every raid. In practice, you usually can.

Grobbulus is an unpopular fight on the tanking forums at the moment due to what are assumed to be new mob pathing mechanics implemented in Wrath. No one's exactly clear on what Blizzard's changed, but the popular theory is that servers are attempting to compensate for player lag by estimating where you're likely to be wow powerleveling based on your movement, rather than where you actually are. This has led to a lot of mobs pathing straight through moving players while aggroing, which is something of a nuisance for tanks attempting to position and generate threat (particularly bears, as Druids do not have 360-degree threat generation).

The reason I mention this is that Grobbulus has this annoying tendency to walk right through tanks while they're kiting him around the room, which requires tanks to move even farther, or Grobbulus to turn around and walk back to reposition himself in front of the tank. When this happens while he's performing Slime Spray, melee in the wow powerleveling vicinity are at risk of spawning a Fallout Slime as they will suddenly be within Grobbulus' hitbox. Melee were never great on this fight to begin with due to his Poison Cloud, but the Wrath pathing mechanic has made them more of a liability, and my guild doesn't use any melee on Grobbulus in part because of this.