I think I started a thread similar awhile ago. Yeah , a chopper to me means ya seriously alter a stock frames geometry. A 'bobber' means ya left the frame basically stock , but 'bobbed' all the unecessary parts and sheet metal off to save weight.
I think the word 'custom' is too broadly used too. I mean , they ain't really 'custom' parts if they're a production item , bought from a catalog , and used as purchased.