Bobbers vs choppers

Bobbers are related to choppers in that they represent a minimalistic approach where the motorcycle is stripped of parts or accessories not needed but bobbers generally retain the characteristics of the stock frame.
The principal difference between a bobber and chopper is that bobbers are typically built around unmodified frames. Chopper frames are often cut and welded into shape. Bobbers also often lack most of the chopper's aesthetic characteristics such as chromed parts and elongated forks. Thus, bobbers are fairly easy to create from stock motorcycles and are generally hand built.
The term chopper started to be used from the late 1960s onwards, for motorcycles whose frames had been customized to have a greater angle at which the front suspension protruded with smaller fuel tanks and tall handlebars called ape hangers. For many owners, the difference between bobbers and choppers doesn't come down to what's on the motorcycle but what isn't on it and whether it has a short front end or a long front end, stretched suspension defining it as a chopper.
Whereas customized motorcycles can be extremely expensive, bobber builders tend to adopt an economical approach involving old, second hand, recycled parts and hand machined items redolent of the period before the mass-market motorcycle accessory industry had developed.