What Idol Groups in Love Live have real life counterparts?
In Japan, they are generally called as seiyuu unit (Japanese Wikipedia) when a music/acting unit (group) consists of voice actors. For a special case where a group also works as a real-life idol, it is called seiyuu idol unit.

According to the Wikipedia, there are 3 units, but only 2 are seiyuu idol units:


A-RISE (created for Love Live!, no live event/talk)


Kira Tsubasa: Sakuragawa Megu
Toudou Erena: Matsunaga Maho
Yuuki Anju: Ohashi Ayuru

μ's (created in 2010 for Love Live!, 6 live events, 4 live talks, 18 guest appearances)


Kousaka Honoka (Leader/Printemps): Nitta Emi
Ayase Eli (Bi Bi): Nanjo Yoshino
Minami Kotori (Printemps): Uchida Aya
Sonoda Umi (lily white): Mimori Suzuko
Hoshizora Rin (lily white/NikoRinPana): Iida Riho
Nishikino Maki (Bi Bi): Pile
Toujou Nozomi (lily white): Kusuda Aina
Koizumi Hanayo (Printemps/NikoRinPana): Kubo Yurika
Yazawa Nico (Bi Bi/NikoRinPana): Tokui Sora

Aquors (created in 2015 for Love Live! Sunshine!!, 2 live events, 5 live talks, 3 guest appearances):


Takami Chika (Leader/CYaRon!/Gu~RinPa): Inami Anju
Sakurauchi Riko (Guilty Kiss): Aida Rikako
Matsuura Kanan (AZALEA): Suwa Nanaka
Kurosawa Dia (AZALEA/Gu~RinPa): Komiya Arisa
Watanabe You (CYaRon!): Saitou Shuka
Tsushima Yoshiko (Guilty Kiss/Gu~RinPa): Kobayashi Aika
Kunikida Hanamaru (AZALEA): Takatsuki Kanako
Ohara Mari (Guilty Kiss): Suzuki Aina
Kurosawa Ruby (CYaRon!): Furihata Ai