Short answers, pulled from the story.
Political economy is an interdisciplinary field that studies the mutual relationship between political and economic systems, including how the state shapes markets and how economic interests shape politics. Economics, by contrast, typically refers to the narrower study of the economy without broader political and social considerations, a separation that became formalized after Alfred Marshall's Principles of Economics in 1890.
The phrase économie politique first appeared in France in 1615, in a book called Traicté de l'oeconomie politique by the French soldier-economist Antoine de Montchrétien. The term was later translated into English as "political economy."
The world's first professorship in political economy was established in 1754 at the University of Naples Federico II in southern Italy. The Neapolitan philosopher Antonio Genovesi was the first tenured professor in the role.
William Stanley Jevons developed the marginal utility theory of value in A General Mathematical Theory of Political Economy, sparking what became known as the "marginal revolution" and introducing mathematical methods into economics. He also advocated replacing the term political economy with the shorter term economics, hoping it would become the standard name for the discipline.
According to citation measurement data from Google Ngram Viewer, use of the term economics began to overshadow political economy around 1910 and had become the preferred term for the discipline by 1920. Alfred Marshall's Principles of Economics, published in 1890, was a key driver of this shift.
The 2008 financial crisis prompted renewed scholarly interest in political economy as a framework for understanding what standard economics had failed to explain. The Department of Political Economy at King's College London was formally established in 2010, and the Sheffield Political Economy Research Institute was founded in 2012 by professors Tony Payne and Colin Hay specifically to combine political and economic analyses of capitalism.