what is difference between a Radeon X700 and X1300 graphics card? both are 256mb, pCI-e.?

what is difference between a Radeon X700 and X1300 graphics card? both are 256mb, pCI-e.?

1st X700 is DirectX 9.0b which way it only have pixel shader 2

and X1300 is DirectX 9.0c which means it have pixel shader 3 which is much better, but X1300 has a shared memory "it take a part of it's memory from the RAM which is bad"

and near is a difference in the Clock of both cards, but i really can't remeber
speed of the gpu..the 1300 is faster.