Yeh, I reckon one head is bigger than the other to cater for smaller or larger range screws.It actually has "6 - 8 in" marked on the handle - how that works with an adjustable wrench I can't figure, unless one head is bigger that the other, maybe disguised by the perspective of the photo.
The longer I look at it the more confused I get - is one thumbwheel the opposite to the other, ie, LH/RH?
I can't stand the old Bahco I used to have, with it's thumbwheel opening the jaws when most adjustables would be closing them!