the 465 is technically better than the 460... and by technically i mean before you overclock it.
if you plan on using stock speeds then the 465 will in fact be better. if you are willing to overclock the 465 or even risk bricking the card you can sometimes unlock a 465 into a 470 by reenabling parts of the chip. this makes the 465 a kind of attractive option but again there are risks associated with it.
all in all the 460 if more efficient and mroe overclock friendly for most cases i'd reccomend it... but the 465 might be the best option if you're a real tweeeker and wanna take some risks
The GTX 460 does FP16 calculations in 1 clock cycle, while the GTX 465 does it in 2 (as do the 470 and 480). This subtle architectural difference is so successful the new GTX 570 and 580 adopted it as well. On paper, the 465 has some advantages, but overall the 460 is a better card, and often outperforms the 465, even without taking overclocking into account.