Keanu Reeves and Matt Ryan have each embodied two very different versions of John Constantine. In the DC Universe, John Constantine is known as a chain-smoking demon hunter with supernatural abilities, which was seen in both Reeves's and Ryan's incarnations of the character. However, the respective introductions of Reeves and Matt Ryan's two Constantines also put each on his own distinct path in his corner of DC's movie and TV multiverse.

https://screenrant.com/constantine-keanu-reeves-matt-ryan-biggest-differences/