They have a $5 difference and the plain 650 is 1GB but the 650 Ti is 2GB and the 650 Ti has lower MHz on he core clock and I'm not to sure what that means. So I would just like some help and clarification between the two. Thanks.
The Ti version may have a bit lower core clock speed, but it has double the shaders and texture units. Generally, It performs MUCH better than the non-Ti version(the Ti BOOST 2GB is even better, though).