I thinks they are different disciplines - of course related though. A term like the "political economy" is the application of economic thinking to politics. In that sense economics is is about the flow of "value" whereas politics is about the process of social change. I think there's a tendency to over apply economic concepts in trying to value things it was never meant to though. It's dangerous territory when the economic modelling starts embedding moral judgements, like the value of a human life. That's when the politicians are ceding their morality to the technocrats.