Portable HDD vs. External HDD what to chose?

Hello,

I’m currently considering buying an external hard drive for the sake of data storage and time machine use. I’m considering WD Passport Studio  http://wdc.com/en/products/Products.asp?DriveID=783 as a Portable Hard drive or My Book Studio  http://wdc.com/en/products/Products.asp?DriveID=756 in case I went to select external Hard drives. The Question here, is there any PERFORMANCE difference between external hard drives and portable ones? which is better to get and why?

Thanks in advance,

Rashid

All WD My Passport Studio or My Book Studio are designed with top performance in mind.

USB 2.0 and both Firewire 800/400 connections are there.

My Passport Studio ultra-portable hard drive with customizable e-label is the high performance drive packed with features for Mac users on the go. 

My Book Studio external drives feature a customizable
e-label, automatic, visual backup, and password protection.

The high-performance FireWire 800 interface gives you

the speed you need for creative endeavors like photo and video editing and graphic design.

If you are doing photo or video editing you might want the best.

The WD My Book Studio Edition 2, it has Quad interface,  Lightning-fast FireWire® 800

combined with RAID 0 (Striped) yields the speed you need for smooth video editing,

rendering complex 3D objects or special effects and saving huge blocks of data in record time.