You may have heard this terms being floated around, and when like huh?
It’s simple Maxis or Maxis Match means the CC is trying to stay in the style of the SIMS (Hence the name Maxis which is the company). While Alpha tends to aim to be realistic. It can be best seen in CC such as hair and makeup.
Image credit to https://moongalaxysims.tumblr.com/post/165560797396/bella-goth-makeover-challenge-watch-on-youtube-x
Which should you download?
It is dependent on your preference on how you want your sims to look, and the other point is the Alpha CC sometimes doesn’t work as well as Maxis Match due to the meshes use and seems to clash a bit style-wise. Either way, there is no big downside.