Adata Hardrive HM900 3.5 vs Adata HV320

[acal3000]

What is the difference between They typical The Adata HD320 usb hardrive and the Adata HM900.. I note the HM900 is more robust on design and more bigger I mean the physical 3.5 over the typical 2.5 size I noted something about recording to TV on then drive itself..And it requires an an adapter directly to the power outlet I thought that was not necessary on any modern usb drives anymore so its a by consufing even its design so what are the differences vs usage and so on on both??..