In the UK, moreso years ago than today, an artist would set up their own label to release their tracks, then others (sometimes friends) would release their tracks on that label, so you would see the first few tracks by the same artist before other artists names started appearing ont the vinyl.
Rather than tracks being categorised by 'vocal' 'minimal' etc labels tended to produce tracks that were categorised by their 'sound'. They would sign tracks that would just need that extra bit of input to give it the sound associated to that label, thus it was possible for DJ's to hear a track and immediately identify it by label rather than artist. Usually, because the label was started by an individual all the music released through that label was to the label owners taste.

Someone could probably explain that better and someone could probably argue to the contrary.

Some excellent examples include

Tinrib: (Many of The Captain's back catalogue online for free, legal download.)
ftp://ftp.coreblack.com/TinribVinyl/
ftp://ftp.coreblack.com/TinribAlbums/
ftp://ftp.coreblack.com/DirtyHouseGrooves/
ftp://ftp.coreblack.com/DirtyHouseGrooves/
or go here for his website:
http://www.captaintinrib.com/

Tripoli Trax: In my opinion, the best UK dance label, is now finishing. The shop 'Puregroove' is now turning to Indie music.

Fragile: Mainly the label for Lab 4 but also releases by a few other artists who have the same sound

'React' have possibly been the most varied label, releasing Hard House, Jungle, Techno, Breakbeat and every other genre people call EDM while still retaining a certain sound.

Then there are 'Positiva' 'FFRR' 'Guerilla' 'Manifesto' 'Xtravaganza'. I could go on forever

So it's really all about 'sound' and normally it would mainly include vocals, or mainly not include vocals.

Does that help?