Both are focused on the glamorous lifestyle of the fashion insiders. Lots of expensive brand names and fashion parties! While The Fabulous is more centered around friendships, Celebrity is an over the top drama/thriller.
Both dramas revolve around the IT industry and developing new technology/applications. They both focus on self-driving car technology. There is no sci-fi element in Start Up but overall vibe is similar.
Similar David & Goliath story were an unassuming character tries to take down one of the biggest conglomerates in Korea for the purpose of revenge. Interestingly both dramas mention the autobiography of the conglomerate chairman which is a key plot device.