Both The Brilliant Book 2012 and statements from Steven Moffat have confirmed that they are Mondasian Cybermen. Moffat has also confirmed that the similar-looking Cyber Legion in "A Good Man Goes to War" were also Mondasians. And, while it hasn't been confirmed, it also seems likely that Blood of the Cybermen (from the 2010 Adventure Games) featured Mondasians.
It hasn't been explained in-universe why they look more like Cybus Cybermen without the Cybus logo than like any classic-series Cybermen variants. There are, of course, many fan theories, but none of them have been referenced to by anyone with any connection to the show, or any of the other licensed media.
It also hasn't been explained out-of-universe, although the fan explanations here are less fanciful.
At any rate, as with the Progenitor Daleks, many of the older fans are unhappy with the new Cybus-like look of the Mondasian Cybermen.
- ↑ For example: some offshoot of the time-traveling CyberNeomorphs stuck on Earth in the 2000s discovered Cybus technology and upgraded themselves, or the events of "The Next Doctor" changed history so that the Cybermen trapped in the Antarctic discovered Cybus relics from the 19th century instead of CyberMondasian relics from the mid-20th, or the erasure of "The Next Doctor" and "Army of Ghosts" by the time cracks changed history so there never were any Cybusmen but there was a similar Mondasian offshoot all along, or…
- ↑ Obviously it was cheaper to slightly tweak the Cybus costumes/props/CG models than to design entirely new ones. Also, the Cybermen of series 2-3 are more well-known to the general public than the classic Cybermen, and it's easier to convince many hardcore fans that they're seeing the Mondasians they fervently want to see, than to convince the casual fans that Cybermen are 'supposed to' look like the classic series.
- ↑ Which are in some ways intended to be a return to the classic Daleks, but which look more like the Daleks from the Peter Cushing movies.