Unlike the original "Dead Space," which saw Isaac mostly just adding armor to his existing suit, "Dead Space 2" has a handful of vastly different-looking suits, each of which carries with it some benefits for taking down the necromorph hordes.
If you want to make sure you don't miss any of the suits, you'll want to open up the different power node doors you come across throughout the game. Apart from netting a bunch of cash and ammo, some of the basic suit schematics are found behind these doors.
Once you complete the game, elite versions of each of the suits can be unlocked in New Game +. These have different statistics and color schemes.

BASIC
Name: Engineering Suit
Description: The first suit you'll unlock will look familiar to veterans of the series. It bears a striking resemblance to Isaac's engineering suit from "Dead Space 1."
Benefits: 10 inventory slots, 5% armor
ELITE
Name: Elite Engineering Suit
Benefits: 25 inventory slots, 25% armor, 15% increase in med pack effectiveness.

BASIC
Name: Security Suit
Description: The second suit in the game looks much more futuristic than your basic engineering suit.
Benefits: 15 inventory slots, 10% armor, 5% bonus damage with pulse rifle.
ELITE
Name: Elite Security Suit
Benefits: 25 inventory slots, 25% armor, 15% bonus damage with javelin gun.

BASIC
Name: Vintage Suit
Description: The third suit is a steampunk-style throwback to the original engineering suit design. Think NASA in 1969.
Benefits: 20 inventory slots, 15% armor, 10% discount on store purchases.
ELITE
Name: Elite Vintage Suit
Benefits: 25 inventory slots, 15% armor, 15% discount on store purchases.

BASIC
Name: Advanced Suit
Description: The final suit in the game is the best of the best, and looks like something ripped out of Time Cop.
Benefits: 25 inventory slots, 20% armor, 50% reduced stasis recharge time.
ELITE
Name: Elite Advanced Suit
Benefits: 25 inventory slots, 25% armor, 10% damage to all weapons, 15% increase in stasis duration