"What difference does it make[?]"
So humor me if it makes no difference. I think that the definition of "theory" does not change in a "scientific" context. I think "theory" is not "fact" in any context. So please educate me. I'm more than willing to change my position when my argument cannot hold water. Speaking of water, I can't take my Tylenol without some.
Ps: How can something be both theory AND fact at the same time? Once proved, theory becomes fact, no?
No. "Fact" is what happens. "Theory" explains how it happens. One never "graduates" to the other. They cover different aspects of description.
Here: Evolution is a Fact and a Theory. And I sense another question coming on, so also see: 29+ Evidences for Macroevolution: Scientific Proof?.
And yes, the meaning of "theory" in a scientific context really does matter. In common usage, "theory" means any potential explanation, including something you just dreamed up after two seconds of thinking and put forth as just a wild guess. In a scientific context, this is *not* what it means. In science, a theory is a coherent group of general propositions used as principles of explanation for a class of phenomena, which has passed a number of validation tests and has made successful predictions which enable the outcome of various tests. In short, a "theory" in science is not just a guess, not "just a theory" in the vernacular sense, it's a very different kind of thing with a far higher level of validation and confidence. It is perhaps unfortunate that the same word is used for the layman's "just a guess" on the one hand and the scientifically tested propositions on the other.