The title is supposed to have some irony in it, because with bodybuilding, you cannot have one without the other.
But it's a concept I think that many beginners/intermediates really struggle with (including myself at times in the past).
There seems to be 2 phases that many lifters go through.
One phase is the strength phase (aka "ego phase"). This is the phase where they realise that their training needs to be intense. So they drop many of their filler exercises (redundant exercises). They fall in love with making jumps in load and low rep training. Some people respond well to that type of training (often referred to as power-building), but this is not aimed at them.
Before long, they begin to realise that their size gains don't seem to match the strength gains they are making. They realise that tension/volume on the muscle is pretty low, and much momentum is used. Often they find things stagnating because they confuse themselves with some hybrid of powerlifting and bodybuilding (powerlifting needs to be more structured especially with regards to rest/frequency/intensity). Sometimes, depending on how extreme they became, they begin to realise that their body is developing imbalances (typically those who focus just on the "showy muscles" or some form of pure "starting strength" training).
The other phase is where they realise that a pump is not JUST a pump. They begin to realise that ability to achieve a healthy pump in most of the target muscles is ideal. Instead of making fun of the bicep curlers pumping away, they begin to join the group (lol hypocrites!).
But, they often go to the extreme, adding in too many exercises/sets JUST for the sake of it, and start to "forget" about strength progression. They put a little bit too much emphasis on the feel/form when in reality, it doesn't matter how many exercises you do, or how many sets, and no amount of perfect form and control will make up for no decent muscle over-load.
Each phase doesn't necessarily take any specific order, but it's not until the person comes to terms with both, a happy medium, when their gains really take off (assuming diet is in order).