I hesitate to use the word "fact" unless we discuss matters of law or practice, where all have agreed.

Scientific axioms are those very few principles that we know we can always take for granted -- but even axioms have a few problems, which we call exceptions.  One axiom is the Pythogorean triangle formula: h^2 = O^2 A^2

Scientific laws are "Proven theories that apply regardless" (usually named for the scientist who first rigorously proved it) do not carry the weight of axiom, but we can rely on them consistently.  Newton's laws of motion are good examples.

Theories are "tested solutions to observed phenomena."  Relativity is one example.

Hypotheses are "un-testable observations in nature that remain open to interpretation."  Evolution is one such hypothesis.

Terms like "putative" and "speculative" mean that the idea makes sense but there is no way to prove it.  Tachyons and light exotics are "putative forms of matter."  However, the math must work and the idea must be sound enough to take it seriously. 

Ideas all start out as "putitative" and once proven (not necessarily "accepted") it becomes a theory, once settled, it becomes a law, and once left with no feasible question, it becomes an axiom.