What's an RSS aggregator? I've heard the the word aggregator used for what, in my mind, are very different pieces of software. And in fact, in describing the app that I've been developing, I too have been caught in this nomenclature trap. And by the way what's the difference between an aggregator and a syndicator? Is an aggregator a personal syndicator? It's not that people don't have precise personal definitions for these words, it's that we are lacking common definitions. And particularly if we want to talk to our users it's critical that we be consistent, and it would certainly help if the words we use had some intuitive basis.
Agreeing to terms is perenially difficult (impossible, actually.) I might even argue that it's early to be trying to nail down the 'right' term to use to describe something, given that those somethings are constantly morphing, changing, and combining into other things.
I don't want to presume to choose the terms. I've tried to capture what I've heard and write it down in the form of a framework. Here is a cut at a framework.