You're looking at two drawings and assuming they're factual
While the first drawing is a simplification for the purpose of showing basic structure and operation and the second diagram is more complete with substrate effects and doping diffusion (even it's not "complete"), the problem here is that you're looking at images in a book and assuming they represent very different things.
Why would you assume that? Not meant to be an offensive question, it's just odd that you do.
In reality, there's nothing stopping a manufacturer from building a silicon cube and plopping a gate on all six sides — in which case you could "factually" claim that JFETs are manufactured in vertical, horizontal, right-side-up, and up-side-down configurations — but in reality there's just the one type of JFET.
It's worth noting that there are many ways to build a JFET just as there are many ways to build a car. Back when I was designing, it was common to create interdigitated FETs (the gate was built as two parallel strips of SiO2 drawn like your two hands with fingers spread apart and brought together so the fingers of each hand overlapped). That minimized the capacitive charge required to actuate a very large FET. We also had FET designs that looked precious next to nothing like a regular transistor that were used for ESD discharge circuits and the active loads on current sources.
Don't get too hung up on how things are drawn in books. Unless specifically told otherwise, assume they're different ways of showing you the same thing for the purpose of highlighting specific concepts.