Same male lead, some of the supporting cast is same
Both have some elements in the story which goes against the social norms
Most importantly, same Director Ahn Pan Seok and same Screenwriter Kim Eun, hence that's why they kinda feels like giving same vibes but indeed both are great dramas and actors are great they did there work really well!!

although Two Lights: Relumino is a light hearted, very beautiful short film on the other hand Always is a classic heart wrenching movie. A common thing in both movies is that actress is visually impaired........ But everything else is different, both gives different feels :)