Meaning is what is fixed by the conventions for the use of expressions that we learn when we learn a language. In contrast, content is a property of individual utterances.
Content is tied to truth-conditions.
First I need to make some distinctions and develop some concepts about propositions. I will not need to adopt a specific and detailed ontology of propositions and their components for the purposes of this essay. There are two main approaches to propositions in the literature today, the classic conception of a proposition as a set of possible worlds, and a number of conceptions of structured propositions. I'll think of propositions structurally, but borrow the possible worlds conception when convenient to get clear about things. The distinctions I need can be made in any number of more detailed approaches.