That’s exactly it – the limiting factor is your slower usb1 (actually usb1.1) drive/interface. Yes, the larger slot-style plugs are the same for both (there’s a mini connector for things like phones/cameras etc)
You’ll always get something distinctly less than the raw usb speed.
Eg the 480 Mbps figure (60 Mbytes/s) is the base signalling rate, *not* the effective data rate, and doesn’t include a whole lot of overhead in the usb protocol (ie how the signalling works). The maximum rate you’d get in practice would be about 52 Mbytes/sec, in reality with a recent PC it might achieve 32-45. If the disk drives keep up of course 🙂
Should you care 😉 – a usb2.0 host (generally a pc) has to support High speed (480MBps), Full Speed (12MBps), and Low Speed (a whacking 1.5Mbps) ‘cos any of that lot may be connected to it – your usb1.1 device will run at 12Mbps peak. A keyboard or mouse would probably be Low speed.
I suspect you’ve got a usb2.0 hub, but if you were using an old one that was usb1.1 a similar thing would apply – except now a usb2 drive connected to the pc via that hub would just work at 12Mbps, since the hub would be the limiting factor.