What is MCU and DCEU?

The Marvel Cinematic Universe is the name given to the series of films created by Marvel Studios that allow characters from one film to interact with characters from another film.

In short, because of other film studios such as Sony and Fox was producing films based on Marvel characters such as Spider-Man and X-Men, Marvel wanted to produce films where they would have creative control over their characters and allow them to reap the most profit.

The first of these films was Iron Man, which was followed by Captain America: The First Avenger and Thor. Characters from Iron Man, such as Agent Coulson, an agent for the spy group S.H.I.E.L.D. appeared in those other films, showing that these films were interconnected in the same 'universe'.

 In the same way that Marvel and DC have their 'primary' Universe where characters regularly interact with each other, as well as alternate universes where the same characters are given a different form. For example, Miles Morales is the Spider-Man in the Marvel Ultimate universe, while Peter Parker is still Spider-Man in the primary Marvel universe. The Marvel Cinematic Universe, or MCU for short, now includes 20 films, as well as TV series such as Agents of S.H.I.E.L.D. and Agent Carter on ABC and Daredevil, Iron Fist, Jessica Jones and Luke Cage on Netflix and cartoons.

The DC Extended Universe is the unofficial term for the media part of the DC universe. It includes all the film that shares the same universe. The film series that began with Man of Steel and has continued with Batman Vs Superman: Dawn of Justice, Suicide Squad, Justice League and Wonder Woman and the and the upcoming installments on the film side like Aquaman and Flashpoint.

I think it is only limited to the specific cinematic universe. I do not think any of the TV shows from DC are part of it. Traditionally, Warner Bros. has kept their TV shows separate from their film universe. The bulk of the popular DCTV shows are set in the so-called "Arrowverse," and in theory, this allows DCTV freedom to maneuver, not having to consider the latest big-screen developments. So they may be a part of different universes. Unlike Marvel Cinematic Universe(MCU) which includes TV shows set in that same universe. But with the new upcoming DC’s television series Titans that will air this 2018, I think this should share continuity with the DCEU.

If you have questions, clarifications, and suggestions, feel free to comment.