There are two totally different patterns of knives being shown here. One thing they have in common is the general type of blades they contain. Otherwise, totally different. The first few pics describe a knife about 3 5/8 inches, with a swell center, often with "balloon" bolsters. Schrade 863, Camillus 72, and others by Western, probably CASE, maybe more. The 2 springs are typical configuration for a slipjoint. They are often called a whittler, but do not fit the classical definition of a whittler, either by how the blades are let into the frame or by the springs, which are not wedged. As far as I know, the word "carpenter" to describe this pattern, was only used by Camillus, although I could be wrong.
The second pattern germane to the discussion is the one you see in later pics in this thread, about 3 7/8 inches long. Also made by all major companies, it is a true whittler in the classic sense, meaning that it has two springs, separated by a wedge. The master blade is by itself and rides on both springs. On the other end of the knife are two secondary blades which use only one spring each (obviously). This pattern was USUALLY referred to in the literature with the word "carpenter."