Socket AM2+ is a CPU socket, which is the immediate successor to Socket AM2 that is used by several AMD processors such as Athlon 64 X2. Socket AM2+ is a mid-migration from Socket AM2 to Socket AM3 and is fully compatible with Socket AM2, so that processors designed for Socket AM2 work on Socket AM2+ motherboards and vice versa
Am2+ has a faster standard of ddr2 memory, also more expensive.
Also, Am2+ offers hypertransport 3.0.
A more technical reference can be found online, such as http://en.wikipedia.org/wiki/Socket_AM2%2B
am2+ wont work on a amd motherboard. Am2+ allows 1066MHZ ddr ram. If you are using a althon x2, either buy a new one or buy a am2+ compable motherboard and put a phenom x4 cpu. You will see that its worth it .
There is motherboards that have AM2 and AM2+ which I have a motherboard of one vendor. Very cheap. I needed a new motherboard so I picked up that one as it was the cheapest. So if I ever need more CPU power (I don't) I can pick up an AM2+ chip.