Well I still think the big difference is fatigue.
Clusters, you are using a specific weight for a set number of total reps.
Rest-pause, you are using a specific weight, but the total number of reps will be dependant on fatigue.
Fatigue is to be avoided with clusters, and is one of the goals with rest-pause.
Also, like you said, clusters generally have the same number of reps per set, whereas rest-pause the number will decrease.
I think these definitions are pretty good, but im not sure if they are an agreed upon standard. I think it is safe to also state that rest-pause is a TYPE of cluster training.
But aside from definitions i'd like to hear people's experience/opinions on the two methods.
Im very suprised that you dont hear more about both of these methods. In all of the westside stuff ive read, ive seen no mention of either, but I know many of the guys use these methods.
My biggest concerns with these methods is over-using them. If somewhere to go extreme with westside and these methods I could see them using clusters instead of all ME work, and rest-pause in place of DE work. And I think this would definately be overdoing things.
I dont think clusters are necessarily fatiguing if done correctly. If I were to do 3 x 1,1,1 in place of ME with about 90% 1RM this would be 9 total reps. In a typical westside ME day working up to a 1RM, I would expect to get about 3 reps at >90% 1RM. Im sure the average load lifted would come out to about the same, but the normal ME method would take a lot longer due to longer rest breaks.
So I can already see advantages/disadvantes to clusters depending on the person. A high level pl'er might do better to work up to a 1rm. 3 reps greater than 90% might be a lot of volume for them, and more importantly lifts in the 95-105% range are going to be more necessary for a higher level lifter. And long rest breaks will be optimal for maximal recovery
On the otherhand, a lower level lifter or non-powerlifter needs more reps, and can benefit from shorter rest breaks. 5 minute rest breaks might allow more recovery, but probably aren't needed.
so the use of clusters is pretty simple IMO.
but, rest-pause is a bit more copmlicated. I can see rest-pause easily being overused if someone uses it often for bench, squat or deadlift. So to avoid this, I'll probably avoid rest-pause on any movements that I tend to train heavy on.
So as of now, im thinking of this.
Clusters: Flat benching (cg bench, comp bench, floor press, board press, rack lockouts)
Squatting (back, front, zercher, rack)
Deadlifts (sumo, deficit, comp, rack pull, rdl)
DB presses (incline, flat, floor press)
Isolation work (like leg curl, or shoulder raise)
So thats what im thinking, but im not sure how often these can be used. Like can clusters be used EVERY ME workout if you rotate the exercise each week.
So its gonna take some trial an error, but Id like to go into things knowing what others think and have done.