演唱会 vs 音乐会 difference
演(perform)
唱 (singing)
会 (gathering)
演唱会  = (singing) concert

The key word is '唱'. No matter it is a solo or a group concert, the performer(s) will sing songs.
Sometimes instrumental music might be inserted in the program, but the majority of the show is about singing

演奏 (perform musical instrument)
演奏会 = (instrumental) concert

The key word is '奏'. In a instrumental music concert, the performer(s) will perform instrumental music.
Some singing performance might be added as bonus, but the main draw is the instrumental music

音乐 (music)
音乐会 (music) concert

A music concert can be a mix of singing and instrumental music.
演唱会 and 演奏会 mostly refer to concerts performed by professional singers or musicians and you have to buy ticket to attend
However, free events with amateur performers can still call themselves 演唱会 or 演奏会
Commercial 音乐会 (music concert) are relatively rare compare to commercial 演唱会 (singing concert) and commercial 演奏会 (instrumental concert)