John Willshire wrote a good post on the difference between fidelity and resolution in design. From Want to improve your design process? Question your fidelity:

For us, fidelity is all about the people axis; how close is this to the real world? That’s the future point, when the product is out in front of lots of people, being used often, at scale. If you want to increase fidelity, then you show whatever you have to more people.

Which leaves the vertical axis, things, to be all about resolution. Resolution is a much more technical description of what we have in front of us, used across many different fields to description the detailed specifications of what the thing involves. It’s been much more useful when you’re using that language around the thing you’re working on.

There are some good illustrations in the post to make the point clear. I think this is a pretty important distinction, since it shows how user feedback can be helpful during each phase of a project.