Sure I can remember, depends whether I like the band or not. (Let's see, Robbie Robertson, um...)

Girls Aloud I can only ever recognise the ginger one (Nicola), and Nadine, because she does the singing - at least, when I saw them at the Big Gay Out once, she was the only one who wasn't miming for most of it. The others aren't memorable, nice but not memorable. Unlike e.g. the Spice Girls where they all look and act and sing differently.

Frida usually takes the lower vocal lines and Agnetha the high lines. See Money Money Money for an example.