@Manu I am replying to you here as distinct from a comment as I ended up typing a bit more than I initially thought… Oops… :o
The answer to your question directly:
The hypertrophy templates have more volume which is better for maintaining muscle tissue on a caloric deficit.
The more nuanced answer (still a bit light as there is much more to it):
The key point is that body fat is lost through diet. However, the amount of muscle retained is (assuming protein needs are met) due to programming. On a fat loss, the key is to keep as much muscle as possible. This is the same as trying to gain as much muscle as possible if on a caloric surplus (within moderate limits, not a dirty bulk). The only difference is the caloric intake. The literature, and it seems the bros had this right, shows that volume is the key to increasing muscle size. So training for muscle size and cutting calories (again moderate deficit, there are other posts across this forum on this topic (some info here with further links therein Not so lovley love handles - Nutrition Discussion - Barbell Medicine Forum)) result in the maximum retention of muscle mass. This is done by taking fat loss long and slow and by training for hypertrophy. If one is training to gain muscle and the limiting factor is caloric intake, the body will likely retain as much muscle as possible.
Training for strength includes some volume; this is as part of the strength equation is hypertrophy, but the other parts of the strength equation are skill (i.e. in able to handle a single max effort) and neurological adaptations (i.e. with the muscle you have can you (i.e. your brain) use all the muscle fibers available to it). This is why on a fat loss you can gain strength, but as training is specific, training for strength will train more skill and neurological factor and less hypertrophy, which inevitably means some muscle loss on a caloric deficit .
Bodybuilders train with high volume (sometimes too much), they don’t care about weight lifted (to a point) and use diet to manipulate calories and end up incredibly lean, both natural and chemically assisted. The process is the same between the two. The volume training is there to keep the muscle loss to an absolute minimum (some will inevitably be lost, that is how the body works, but we want to minimise it as much as possible).
If your goal is to get as shredded as possible and maintaining all muscle possible, it is hypertrophy training all the way down. However, I guess most on this form want to also build strength. As training is specific (there it is again), you need to pick a specific goal(s) (long, medium, short) and work towards those.
For example: I am looking to get leaner, minimise muscle loss, but also minimise strength loss. Thus why it has been hypertrophy for the last few blocks. However, I am itching a bit to consolidate and increase strength while keeping body fat where it is. So I plan to slowly increase calories next block while doing Bridge v3 and then likely resume fat loss on a Hypertrophy v3 4 day. I started to focus on slow body fat loss in September/October 2018 at around 89kgs with a 97cms waist resulting in around 24.5% body fat and circa 67kgs lean body mass. I am now 84kgs with a 90cms waist resulting in around 19.5% body fat and keeping at circa 67kgs lean body mass (yes I record and track all these stats), with minimal loss in strength (keeping my 1@8s at PR levels, or just short of). So my short term goal is being accomplished. My new short term goal is to change next block to build strength and keep body fat where it is (emerging strategy type view of the next block). My medium term goal has been and is to get down to 12% body fat which translates to around 75kgs at 80cms waist, while keeping strength at current levels. My long term goal is to max out my muscle mass (I add some bro work in my GPP for delts/calves/arms) and strength while staying between 12% to 15%. My projected maximum weight at 12% body fat is circa 93kgs which has a 80cms waist circa 82kgs of lean body mass, which admitted is just a guide and a rough projection. That is a gain of circa 15kgs of lean muscle and despite being a rough projection, it is a goal to work towards. The long term goal needs me to get to 12% first and then slow muscle gain bulk and strength gain to 17% (I don’t want to be fatter), lean down again to 12% while keeping all muscle gained to that point and strength gained to that point, then slow muscle gain bulk and strength gain to 17%, rinse and repeat ad naseum.
.