How do the DC TV series compare to the DC Extended Universe (DCEU) films in terms of continuity?

Historically, the DC TV series and DCEU films had very little continuity. The 'Arrowverse' operated as a largely separate universe. With James Gunn and Peter Safran now overseeing both film and television, the goal is to create a more unified DC Universe. Future TV series will be more closely integrated with the new DCU film slate, but the existing 'Arrowverse' shows are generally considered separate continuities.