Hwang In Yeop is in both dramas

Both are about romance and break ups

Both have nice cinematography

Both were webtoons first. Both have bright cinematography and are light hearted

Both are funny and have romance. True Beauty is more focused on romance though.

Both have elements of high school, although True Beauty is set in a high school whereas it's a side plot in Backstreet Rookie

The ML in Backstreet Rookie is much nicer to the FL than the ML in True Beauty is to the FL.

Both have funny side characters

Both show sibling relationships and friendships

ML in Shopping King Louie is rich (but loses his memory)

Both are light fluffy romcoms with lots of cute moments

ML in Shopping King Louie becomes much nicer and adorably cute (and a bit stupid) after he loses his memory but is the brooding type before then.

Both are about webtoons

W is about the FL going into the webtoon and then meeting the ML whilst True Beauty is a webtoon itself.

Both have bright cinematography and are fairly light romcoms

Both involve MLs that are quite stoic at first

Both involve affairs and a missing child

Both have issues between the married couple and one being unfaithful

Both have other individuals helping the leads

Both in the crime/mystery/ thriller genre

Secret Mother doesn't have communication between past and future