I think the big dividing line between what many animals do and what cells or plants do is the ability to react in different ways by considering stimuli in conjunction with memory, and then the next big divide is metacognition. I feel like there should be concrete words for these categories. "Sentient" and "conscious" have pretty much lost meaning at this point, as demonstrated by this discussion's existence.

I will call them reactive awareness, decisive awareness, and reflective awareness in the absence of a better idea.