The advantage of fitness without equipment is that it pays more attention to fitness in a lively and relaxed way, explaining and training some basic movements. It is a very suitable book for people who want to do physical training but don't want to go to the gym or have too much time for physical training.
The advantage of prisoner's fitness is that it provides a unique fitness concept, that is, to exercise under extreme conditions by repeating relatively simple actions. This method is difficult, but it is a good choice for people who want to challenge themselves and pursue a higher level of fitness.
In a word, fitness without equipment and fitness for prisoners have their own advantages, so you can choose suitable books according to your personal situation and needs.