The New Gear 2 is said to be thinner and lighter (68g) sporting the same 1.63 inch AMOLED Display powered by 1GHz (from 800Mhz) Dual-Core Processor complimented with 512MB RAM and 4GB Internal Storage. Packs that 2MP HD Camera and brings in improved health sensors and infrared blaster.

Oh on the battery side it packs a 300mAh (smaller than the original) which promises to be more energy efficient and Samsung claims to run about 2-3 days.
On the flip side, the wearable is now IP67 certification for resistance to water and dust great for those adventure junkies...
The New Samsung Gear 2 comes in Charcoal Black, Gold Brown and Wild Orange while the NEO variant has Mocha Grey. Global release date is said to be in April but no pricing as of now.
Sources:
engadget
gsmarena