okey so basicllly
There is an AKB FAMILY (there is no such name but lets just name it like that)
They have under them
FIVE main groups
- AKB48
(main group - they had their own theather in akihabara (Tokio) where they performe STAGES - stage is like a musical but without any plot just dancing and songs they have concerts (sometimes with other AKB family groups), release singles and albums)doing tv shows , etc
* the diffrence between stages and concerts are that concert can have songs from many stages , singles , album songs
fiour TEAMS - A , K - B and 4 - each team have their own STAGES
there is also AKB Trainee Team - they are in traing members who when official members graduate from any team are filling their spot - Trainee Team got their own stages too
- SKE48 ( Teather for SKE is in Nagoya , teams S, KII (K-2 since team K is already in AKB ) , E and Trainee Team. Pretty much like akb )
- NMB48 (Teather in Osaka they are on the begining - there is just Team N and Trainee Team the same idea all over again)
- HTK48 (those are not formed yet - auditions are on start)
there is also
SDN48 - This is like AKB but shows are more mature and for adult people
they had generations instead of Teams
But its prety much the same concept
AKB also had
units
they are like mini bands - made from AKB members
sometimes they release one single (Like natto girls to promote Natoo Day)
and sometimes they are long term groups like no3b
girls from units work in unit and AKB at the same time
some Members from SKE i NMB sometimes perform in AKB singles becuase of their popularity among AKB fans