In order to learn pull-ups one has (omongst others) two options if xe can't do real pull-ups, yet: Negative pull-ups and assited pull-ups.
With negative pull-ups one basically omits the contraction and focuses on the eccentric movement, be it with the help of a chair, by juming or whatever other means.
Assisted pull-ups on the other hand work by decreasing the weight one has to move, e.g. with resistant bands.
While the movements are somewhat similar, the exercises are fundamentally (or at least substantially) different. While the negative pull-ups have the merit that they work with the full weight the full pull-ups will be working on they omit half of the motion and especially the initial pull from the dead hang, which is way the hardest for me. Assisted pull-ups incorporate that initial pull, but the structure of the force withing the exercise is different to full pull-ups (lesser force to apply on the lowest position, more force to apply in upper position).
I'd like to know how those two exercises work differently on the muscles. Basically the same muscles should be in use during the exercises, but I assume that the distribution of the stress should be different. Is any one of those exercises better suited for learning full pull-ups?
(I'd like the answers to be focused not on what's the best way to learn full pull-ups, but I am - parts just out of curiosity - interested in a comparison between those two. If you have suggestions on exercises that are suited better, I'd ask you to please use the comments.)