OK its harder achievement wise and calls for being more aware and focused on a each specific achievement instead of being able to take out 3 or 4 with one swing. Also a lot of the achievement or team based so You'll want to make sure you have at least 1 and best if you have 6 friends who have this game as mutiplayer achievements are really big on AH2. many of the achievements on AH2 are also glitchy in a good way as you don't have to meet the requirements on some of them 100% examples: Fearless, I got in my vehicle on 3 different occasions and killed a total of 5 enemies and huirt the boss while in it and still received the achievement. Also some of the single player stuff can be done in multiplayer too, but it doesn't tell you that in the achievement listing.
Overall I like both of them but AH2 has a bit more replay value and yes, it is longer and ultimately harder, but the new invincibility move is nice.
I'm here to do my very best and if that means
you to get by then I'll do it. Oh and good luck everyone!