The Mid-2011 Core i5 (2.5GHz Dual Core) Mini came with Radeon 6630M Graphics, While the newer late-2012 Core i5 (2.5 GHz Dual-core) Mini features at best Intel HD 4000 graphics, which are up to 15% less powerful. 500GB HDs and 4GB of RAM are standard on both models.
What you are paying for is the new USB 3.0 ports, a definite plus for many, but not all. Thunderbolt ports are available on both the current and previous gen. The dedicated Radeon 6630M excels at HD video editing and moderate gaming whereas the HD4000 is limited to simpler every day tasks such as HD video playback and lite gaming. The HD4000 graphics of the newer 2012 Mini are certainly capable of providing and adequate environment for photo and video editing, but if you do either everyday, you will love the extra speed from the dedicated GPU in the older Mini.