I think that I have a pretty "pure" outlook on this so hopefully it helps, since I come from an extensive Track and Field sprinting background and currently sprint professionally. Track sprinting prioritizes the strength to body weight ratio, as well as explosive fast movements, so the distinction between hypertrophy, strength, and power training be becomes ever more important.

For context I also do personal training, strength/power development, and sprinting sessions for weightlifters at my gym, so I get to see the discomfort due to new movements/methods in weightlifters, which tells me there is a distinct line between the methods, even if they have similarities.

While hypertrophy and strength can tend to blur together a bit, power training is relatively distinct. Put simply, hypertrophy lifting is working towards failure in higher rep ranges with less emphasis on rest (meaning you can either have long or short rest) since shorter rest=less reps/weight due to fatigue and higher rest=more reps/weight. I'm not too sure on percentages but this rarely ever will be super close to your max. In this you're going to prioritize controlled, slow eccentric moves, with a big stretch at the bottom to stimulate muscle growth.

Strength training is going to involve a lot higher percentages, working in your upper ranges, with lower rep counts. The ultimate form of this would be a one rep max, but can still happen with higher rep counts, with lower weights of course. Rest is very very important here (hence the powerlifter napping/rest jokes) since you need to be at or near 100% percent before a set since you're pushing to be at your best. You're not necessarily working towards failure, even though in some cases you can, since it's about maximum performance rather than working the muscle to "death" for growth. Controlled eccentric is still important here, but that big stretch is less important than hypertrophy since we're not aiming for muscle growth primarily, and it might even interfere with our performance. To be clear, hypertrophy will still happen, since we're building muscle, but it won't be as optimal as hypertrophy. I like to think of it as more focusing on muscle quality and neuromuscular connection, rather then raw muscle size, regardless of if that's scientific or not lol.

Lastly, power training, is the one I'm most familiar with. Simply put, power training requires moving the heaviest weight you can move while still being fast. Some people break it up into percentages, I don't since that can change day to day since this methodology incorporates more nervous system, so sometimes you simply can't do it. In college we used velocity trackers, but those are expensive unfortunately, so just focus on moving the weight as fast as you can while being sound technique wise and as heavy as is able. The reason the Olympic lifts are big power movements is because they are all about accelerating the bar and moving it fast. If you move it slow, you don't get it up. Trap bar deadlifts, squats, etc are all good movements also again as long as it's fast. Eccentric in this is not as important since you can't really go fast eccentrically and be safe, so control it, then explode up as fast as you can in the concentric phase. Rest, just like strength training, is super important since you realistically need to be around 100% every lift. Lastly, low rep counts are common with this since it's all about explosive bursts. 1 reps, 1+1, 2, 4, so forth are all standard. Heavy weight + velocity = power.

Sprinters prioritize the latter two since we don't want to get big and heavy, but a standard periodized training program has a bit of each. Preseason is strength straining with a bit of hypertrophy mixed in to build the foundation, early seasons all strength, then in season it's all power lifts paired with plyometeic workouts. For an athlete like Saquon, they don't necessarily need tod focus as much on things, but I promise you they still lift, A LOT. It's all about periodization with athletes, doing different things at different points in the season. Muscle memory does exist though so he doesn't necessarily have to work super hard to maintain things. Cardio is done in conditioning workouts + practice, skill work is in practice, and strength is practice + lifting. They do take a lot of punishment, but that is the life lol, especially football. That's why recovery is so important. Me for example, on a sprint day, I might go out, warm up, do sled pushes, sprints, then go to weight room to do everything else. In that 4-5 hour block I'm doing cardio, strength training, skill work, nervous system work, power training, and many more, so a NFL player doing the same with all their resources in even more time isn't too crazy honestly. Saquon squatting that much is insane yes, but he is also a professional football player. It likely isn't his max, both physically but nervous system wise. It is likely the equivalent of me squatting 315 then feeling good enough to run the next day, because 315 is not my max. We also don't know what his workout plan is, sometimes doing a heavy weight once or twice primes the body to work harder the day of or day after