difference in external hard drives

[elitejp]

Im looking at getting an external hard drive and assumed that I might as well get a 1tb due to the bang for the buck compared to say even a 160gb drive. So heres the question what is the difference between an external hard drive (3.5 inch) and a portable external hard drive (2.5inch)

heres something im looking at:
http://www.tigerdirect.com/applications/searchtools/item-details.asp?EdpNo=3718396&csid=_27

 

[Zatharus]

The only differences between a 3.5" and 2.5" drive of similar capacity and RPM is physical size and sometimes the connector (IDE primarily - SATA connectors are identical). Also, some 2.5" drives will offer slightly faster seek times due to the heads having to travel less distance.

Edit: One more advantage with 2.5" drives is that most of them can be powered directly through the USB or Firewire bus.