Colloquially they're used interchangeably but the dictionary definitions (and therefore usage in maths and the sciences) are different: Theory: A set of statem

Colloquially they're used interchangeably but the dictionary definitions (and therefore usage in maths and the sciences) are different: Theory: A set of statements or principles devised to explain a group of facts or phenomena, especially one that has been repeatedly tested or is widely accepted and can be used to make predictions about natural phenomena. Hypothesis: A tentative explanation for an observation, phenomenon, or scientific problem that can be tested by further investigation. Examples: the Special Theory of Relativity (very well tested, and used for real world applications), and the Riemann Hypothesis (a result in mathematics that appears to be correct but so far has not been proven).