In the everyday world, there really isn't too much difference between a scientific theory and a law. Both are used to describe well-documented explanations for how the universe operates; the main difference is that a theory leaves room for itself to be disproven by someone else; the word 'law' is saved for things scientists consider effectively settled once and for all.
Thus, Einstein's Theory of Relativity, which holds that light can be deflected by gravity. It's a theory because of quantum mechanics, deemed incompatible. I'm going to straight-up admit that I don't know what the hell words I'd be writing, even though I can tell this is kind of important for all the sciencing going on out there and really should pass it along, so let's just leave it at the fact that scientists found a neutron star orbited by a white dwarf, which they figured might be enough to cause the theory to break down because black holes make it break down and this was also really tiny and really heavy, they used a telescope at European Southern Observatory in Chile to look at it, and it didn't. Because of... reasons.
You're really better off clicking the links than listening to me try and stumble through it. Honestly, it is way over my head.