Himeno said:kyouon said:
Similar at micro-level but vastly different at macro-level.
K-On is a CGDCT anime at its core with music as a supplement. It is more relaxed in nature as it revolves around school activities.
BangDream is a multimedia franchise with its rhythm+VN gacha game as its main focus while anime and live performances are used to promote the game. Therefore, it can be flexible in both music and anime genre such that it is CGDCT at micro-level but more music at the macro-level. This is because it currently has 5 bands in the franchise with 2 more coming soon.
You can jump into the S1 anime without any prior knowledge because it involves only one band, Poppin Party which is closest to K-On. But with S2 & S3, you'll need to know the other 4 bands officially through the game. Fortunately, you can also just read the VN stories and interactions online to know more about them without needing to download the game.
Also, 2 out of the 5 bands actually have real band/seiyuu counterparts. The two new bands have them as well. This means they can keep making live performances to generate new fans and revenue. So it is much more ambitious than K-On.
It seems like you might be a bit out of date...
There are currently 5 bands in the game:
Poppin' Party
Roselia
Pastel*Palettes
Afterglow
Hello, Happy World
Poppin' Party and Roselia are also real bands with the members seiyuu playing.
The seiyuu of Pastel*Palettes, Afterglow and Hello, Happy World can't play their instruments (though some are learning), so the 3rd real band, RAISE A SUILEN was created in order to allow the vocalists of the other bands to perform. RAS opened for Poppin' Party and Roselia during Bandori 5th live in mid 2018.
A 4th band was created, Argonavis, which is not part of the main Bandori franchise as it is a boy band. The band has been around for a while, they opened for RAISE A SUILEN at Bandori 7th live in Feb 2019 and were due to have their 3rd live next month (the live has been cancelled due to Covid-19).
The 5th real band, Morfonica, was announced a few weeks ago. They were meant to have their debut in the Golden Week Bushifest (which included Argonavis 3rd and Bandori GBP special live), but it has been cancelled.
RAISE A SUILEN and Morfonica will soon be added to the GBP game.