I haven't played HoN in a while, but from what I remember most things function more like DOTA then LoL. That said, HoN does have a surrender function.
There are a few main differences from LoL.
1) You lose gold on death. This means that if you die consistantly, you will never improve. This leads to a feeder being level 12 half a hour in, and without any better items then he had at 10 minutes. Whereas in LoL, even a feeder will eventually get stronger.
1a) Due to gold loss on death, the losing team will gain strength very slowly. At the same time getting to full strength items takes far longer then in LoL, and a full item carry can kill an entire enemy team on his own with a little skill (with things like crits killing squishy heroes in a single hit from full health, or being able to run into 5 of them and just kill them off one by one then heal to full 15 seconds later).
2) There isn't negative scaling on multiple kills against the same person. This means that killing the same feeder over and over still helps you a ton.
3) There are 25 levels, that means that the frontrunner will keep getting stronger and stronger not just in items, but also in base strength. Almost no one ever gets to level 25 so you can just keep getting stronger, often times losers won't even get to level 15.
By the end of a DOTA game (and from my recollection, its much the same in HoN), typically only a fed carry is anywhere near max potential strength, and losing 2-3 teamfights can take it from near even to very difficult to win.
That said, with proper team comp its possible to turn it around (eg. if you have a late game team and they have a early-mid game team), but turnarounds from bad positions are very very hard, and quite frequently approach impossibility.