premership vs championship

[loosehead3]

how are the teams seperated?is it by population or geographic area?i see there are 4 s.r. teams in the premership and only otago in the championship.better contracts in the premire division?just an old prop from the usa trying to understand.

 

[Kiwiwomble]

previous to the itm cup splitting into prem and champ it was one 14 team comp so they just took the top seven teams and the bottom seven teams