the difference in speed when you download Product Overview (PDF) or User Manual (PDF) you will see in my passport only USB 3.0 and USB 2.0 without anything about speed
if you downloaded Product Overview (PDF) or User Manual (PDF) in my passport ultra you will see USB 3.0 speed 5 GB/s and USB 2.0 speed 480 MB/s
5 years later, these hard drives are still being marketed under the same names, so this topic, which was opened a long time ago, may still be of interest to buyers.
On the My Passport model:
the case is fitted with a USB 3.2 Gen1 micro USB type B connector;
with the drive, the cable supplied has a micro USB type B connector at one end and a USB type A connector for plugging into the PC laptop;
with the My Passeport for Mac model, a second cable is supplied, equipped with a micro USB type B connector at one end and a USB type C connector for plugging into the MacBook.
On the My Passport Ultra model:
the case is fitted with a USB 3.2 Gen1 type C socket;
the supplied cable has a USB type C connector at both end;
a Type C - Type A adaptor is also included to plug this cable into a PC laptop that doesn’t have a USB-C socket;
I have no idea in what way the My Passeport Ultra for Mac model differs (apart from the HFS+ formatting, which doesn’t really matter).
On both models:
speeds are identical on USB type A-B and type C connectors (because all these hard drives are USB 3 Gen1 compatible);
connected to a USB 2.0 computer, the transmission speed of the USB interface is a nominal 480Mbit/s, or ~25Mbyte/s in practice.
connected to a USB 3.0, USB 3.1 Gen1, USB 3.2 Gen1 computer (all these terms refer to the same standard, which has changed name over time), the transmission speed of the USB interface is a nominal 5Gbit/s, or ~450Mbyte/s in practice;
the read and write speeds of these 2.5" SMR hard drives are in the region of 100Mbytes/s, which is well above the speed of the USB 2.0 interface, and well below the speed of the USB 3.0/ 3.1/ 3.2 Gen1 interface.