When a word retains an older meaning along with a newer one, the resulting coincidence can be confusing. When on of the meanings is actually a grammaticalization, things get even more confusing because people try to make sense of the two distinct uses as somehow being the same.
An example is the word “will”. Originally meaning “want” (cf. Germanic languages wollen willen etc.), it became grammaticalized as a future tense marker, much like Latin “habere” in the sense of “have to do” coming to equal a future, “will do”; and ‘going to’ in Spanish and French for a future pretty much ousting the inflected forms.
So when someone says, “I will go to the store,” that is the future tense; but when they follow it up with, “Will you go with me,” that means, “Do you want to go with me.” “Will you?” and “I won’t!” bear that same sense of “want.”