Both shows are airing at the same time and competing against each other. Meanwhile MixNine is mostly letting the world know about trainees from smaller companies The Unit is about idol group members who have already debuted but failed. There will be idol groups debuting at the end of both shows.
It's also a survival show similarly to Produce 101 and Idol Producer alike. It's not too long and has everything you expect to get when you watch a survival show- especially a YG survival show
Both are competition survival programs intended on debuting a KPOP group after eliminating contestants through various challenges.
Members of KQ FELLAZ: Hongjoong, Wooyoung, Mingi and Jongho were contestants of MIXNINE. To get to know these members more, i suggest watching MIXNINE.