PNY's site is vauge. The 4400 has slower memory bandwidth 8.8GB/sec. memory bandwidth vs 10.4 GB/sec. memory bandwidth on the 4600. The 4600 runs at 350MHz but the spec for the 4400 is not listed. They both are 128 MB DDR. I assume the 4600 is just clocked to run faster but overall they are the same card?