There is a very common misstatement and misunderstanding of how adjustment layers work, which I'll repeat here: "Applying an effect to an adjustment layer applies the effect to all layers under the adjustment layer."
That's wrong in a subtle but important way.
What actually happens is that applying an effect to an adjustment layer applies the effect to the composited result from all of the layers under the adjustment layer.
This is an important distinction, because it puts the adjustment at a different place in the order of operations in the rendering pipeline.
Anyway, that's a long and perhaps overly theoretical way of saying that, yes, you may see some difference between applying an effect directly to a bunch of clips compared with applying the effect to an adjustment layer over that same bunch of clips.
