GraphQL was developed by Facebook to be used in conjunction with their frontend GraphQL client library called Relay. Most people opt Apollo + Redux because they were more active early on in releasing open source, and people argue it is an easier learning curve. IMO Relay is a huge win for the frontend to deal with data dependencies; and is a much better design than Apollo + Redux.

GraphQL formalizes the contract between front and back end in a very readable and maintainable way, so they can evolve in parallel and reconcile changes in a predictable, structured place (the GraphQL schema and resolvers). And it allows the frontend, with Relay, to deal with data dependencies in a very elegant and performant way.