[Thinkpad] Hitachi drive difference?

[eletourneau at verizon.net]

Hi. 

I need to replace the drive I run in a Thinkpad 600X . I like Hitachi, but
I'm trying to figure out the difference between these two -- and can't.  
Can anyone teach me?


HITACHI Travelstar E7K100 HTE721080G9AT00 (0A26613) 80GB 7200 RPM 8MB
Cache ATA-6 Notebook Hard Drive - OEM

HITACHI Travelstar 7K100 HTS721080G9AT00 (0A25023) 80GB 7200 RPM 8MB Cache
ATA-6 Notebook Hard Drive - OEM

At newegg, one is $93, and one is $85.  There doesn't seem to a good
explanation of the difference.  Does anyone know?

TIA.