By the way: am I correct that the above posted picture of the Williams Fw07 the car on the leftt is the 1980 model and on the right the 1979-model? The latter one has more that White Lotus 79 feel...
I think you’re right. There isn’t much to differentiate between an A and B model of the FW07, but the B lacked the flip-ups ahead of the rear wheels.
I don't know what pictures you are referring to, but apart of some aero details, you can easily differentiate them because the 1980 model had big 'Leyland' stickers on the sidepods.