What is the semantic difference between apostrophe and single quote?
I see people use both of them interchangeably, but people never create two words to denote one concept. There should be a difference.
An easy way to differentiate:
An apostrophe is only used within or at the very end of a word - it is part of the word.
Single quotes are only used around words - they come in pairs, and are not part of any word.