Identical as far as solo goes. Colonies has an enhanced multiplayer (crossplay with 360+a/some? new game modes). Multiplayer is dead anyway.
Lost Planet: Extreme Condition Colonies Edition includes everything that made the original Lost Planet a hit on PC, as well as the following new features:
New modes for single-player campaign
Score Attack - Each enemy and destructible object has points assigned to them, with the player being awarded different points depending on how they defeat the enemy.
Trial Battle Mode - Take on each of the game's Bosses, one after another
Off limit Mode - Go wild with over-the-top super-charged weapons with unlimited ammunition and increased speed of movement
New online modes
Akrid Hunter Get the chance to finally play as an Akrid as your opponents attempt to take you down
VS Annihilator Each team attempts to destroy its opponent's VS while defending its own
Counter Grab The team with the longest data posts activation time wins
Point Snatcher Take down opponents and collect the most thermal energy points
Akrid Egg Battle Steal Akrid eggs from the opponents team and bring them safely back to your own base
Egg Bandit steal your opponents' Akrid egg, with points awarded for longer capture time
4 new maps for online matches: Crossfire City, Area 921, Lost Arena, Assault Space
5 new playable character models
Multiple new weapons for both snow pirates and the robotic VS suits
Cross-platform Battles Xbox 360 owners can join forces or play against PC gamers
New perspectives - Switch to first person view or the over-the-shoulder view for even more intense action
Some of the single player stuff does sound interesting, but GFWL kind of crushes the deal. I'd go with the other version.