And towards the interpretations of expressions.
For instance, there is a complete difference between reduction to set theory and basis upon an axiomatic system. Probability theory is now commonly done in one or the other way. The latter is sometimes called the ‘Jeffreys interpretation’.
And there is the misinterpretation of Dirac notation by physicists, as referring to physical entities that I assure you do not exist. The proper interpretation is as propositions.