There is an interesting transduality in my experience of sitting practice these days.
On the one hand, there is (often) hardly any difference between when there is sitting (shikantaza) and when there is activity. In both cases, there is – and “I am” – just what happens. There is a field of awareness & phenomena arising in the present, crystal clear, as it is. And that is all there is. The awareness and phenomena appears to be indistinguishable, one dissolved into the other as salt in water as they say.
On the other hand, there is clearly something else happening during sitting practice. There is a sense of deepening, stabilization, intensification even. There is maybe no difference in what is happening in itself, but more like the volume is turned up a little.
So there is not really any difference, and there is a difference as well.