I was browsing some AMD chips on New Egg and I seen many of the the same types of chips with differant names. Such as Manchester, Clawhammer/ hammer, San Diego, and Venice. What do these differant names mean?

They relate to different version of the same chips - the Venice AMDs are the latest ones, and generally a little bit faster than the older Clawhammer ones. Plus they overclock better =)

yea, those just different core names usually meaning a slight architecture difference in the chip itself.

the latesest San Diego and Manchester cores are almost exactly the same as the previous equally rated models, except they added the SSE3 instruction set.

Is the differance huge? I mean if I can get deal on a Clawhammer, will make much differance on performance if I take it over a Venice?

Take the Venice, it runs cooler and has a couple of extra features.

also i believe the new cores use a 90nm process where the old ones used a 130nm process. new cores dont need as much power as a consequence.

nah, they have been using 90nm for a while, IIRC since the Winchester core.