From what I can tell, there are some slight differences from the previous Iron Man 3: War Machine Mark II. The red outline on the arc reactor is now gone and his eyes are now white, not red. He also bares his Iron Patriot decal on his right arm. The other big difference is the Avenger version comes with a Don Cheadle head, which the Iron Man 3 did not come with.
Check out the review on the Iron Man 3 War Machine Mark II that I did awhile ago here
Here is what Hot Toys had to say:
"The much awaited sequel, Marvel’s Avengers: Age of Ultron, will be hitting the theatres very soon! In anticipation of the launch of this epic blockbuster, Hot Toys is excited to present the new 1/6th scale War Machine Mark II Collectible Figure as a Hot Toys Exclusive item! It is also the latest addition to our MMS Diecast Series which the collectible figures are made of diecast material, and realistically designed to look even more like the armor as it appears in the film.
The movie-accurate War Machine Mark II Collectible Figure is crafted with great details and based on the image of Don Cheadle as James Rhodes/War Machine Mark II in Avengers: Age of Ultron. It features a highly detailed head sculpt, metallic black and dark silver colored armor with decals, LED light-up functions, rotatable machine gun, and a specially designed Avengers: Age of Ultron figure stand.
Gear yourself up for this super exciting film and expand your Avengers: Age of Ultron collection with this diecast collectible figure as “War Machine rocks”.
For customers in Hong Kong, special arrangement has been made for pre-order. Please visit Hot Toys-Secret Base Facebook Page for more information."