Batman: Year One worked for both the mainstream DCU and as a prequel to Miller's DKR. In the New 52 universe, the story has many discontinuities and contradictions--starting with the age of James Gordon, Jr.
"You seem familiar with my name, but I don't remember smelling you before."
at the beginning of DKR bruce wayne and commissioner gordan are talking in the restaurant and gordan makes a reference to Batman Year One.
shareThis film is an adaptation of the Frank Miller comic, just as the Year One film was an adaptation of the comic, which was also written by Frank Miller. The Dark Knight Returns was published in 1986, before Year One, which was published in 1987. According to Frank Miller, the Batman in Year One is the same as in TDKR. However, TDKR was never considered canon in the main DC continuity, but much more of an alternate future tale, whereas Year One was considered canon until continuity was changed with the New 52--parts of it have been retconned, though. In addition, these also exist in continuity with the Batman of All Star Batman and Robin in the Dark Knight Universe. This is explained in greater detail here: http://en.wikipedia.org/wiki/Batman_(Dark_Knight_Universe)