Hitachi Deskstar and Cinemastar differences??

Can anyone advise me about the differences between the Hitachi Deskstar and Cinemastar
internal hard drives.

I am seeking a Deskstar P7K500 500GB PATA (IDE) Ultra DMA 133 but everyone is sold out.
I have found a Cinemastar 500GB model but those are not specifically designed for desktop use.

Have also found a Deskstar 320GB PATA which I may have to settle for instead.

Currently have a T7K250 160GB PATA-133 installed as original equipment.
The new drive will be used as a second drive for backup.
Everest shows Max UDMA transfer mode and Active UDMA transfer mode both as UDMA 6 (ATA-133)


Can provide info links to PDF docs if necessary.

Thanks.