The Deepest Philosophical Divide?

I'm going to try and articulate an intuition that I've had for a while, but have never tried to state explicitly before. I think that a very deep, perhaps the deepest, philosophical divide centers on a question about the relationship between similarity/difference and interest. Here are several ways of articulating this question:

Can we formulate a coherent idea of types of similarities and differences that are completely independent of the interests that inquirers have in identifying these types of similarities and differences?

Are similarities and differences themselves dependent upon the interests of inquirers?

Are some similarities and differences relative to the parochial interests of certain inquirers and other similarities and differences independent of inquirers altogether?

Here's where I stand on this question: I think part of what it is for things to be similar and different in a certain respect is for inquirers to have an interest in identifying this respect. If, on the other hand, you think it is possible for things to be similar and different in a certain respect completely independent of whatever interests anyone would have in identifying this respect, then we disagree.

And here's a related divide: do you think that similarities and differences that are dependent upon our interests are somehow or another less than fully real? If you agree with me about the interest-relatively of all similarities and differences, then I think you should NOT think that similarities and differences that are dependent upon our interests are less than fully real. But, of course, some are inclined to think the interest-relatively of similarities and differences makes them less than fully real. But note that thinking that this makes them less than fully real presupposes that for a similarity/distinction to be fully real, it has to be completely independent of any interests anyone would have in identifying it.