Interested in Language
which is the difference between "IF" and "WHETHER"? When should I use one rather than the other?
If you're thinking of their use in subordinate interrogative clauses, the answer is that typically they are interchangeable, but there are a few constructions where "if" is not permitted, for example:
With certain conditionals: We're having liver and bacon for supper tonight, [whether/ *if you like it or not].
With infinitival clauses: I'm not sure [whether / *if to go to the party].
If the clause is subject: [Whether / *if it will rain] is anyone's guess.
Following "or not": Ed doesn't care [whether / *if or not I'm interested in the project].
After a preposition: It really depends on [whether / *if we can get tickets for the match].
Other factors may be relevant, for example style: "if" is arguably a tad more informal than "whether", and some verbs favour "whether", such as "advise", "discuss", "consider", "investigate", "study" etc.
Is that what you wanted to know?