Off the top of my head:

• Belgium (different languages, laws, educational systems, public broadcasters per language region, taxation, etc.)

• UK (different laws in Scotland, different laws in Northern Ireland, education policy, etc.)

• Spain (autonomous regions with their own languages, seperate civil law in Catalunya, Fueros + tax collection in the Basque country, etc.)

• China (the unofficial city tier system, Xinjiang, Tibet, etc.)

• Russia (autonomous regions in the far east, Kadyrov/Chechnya: strict alcohol prohibition and possibly years in jail, etc.)

• India (IRC autonomous administrative divisions can make their own laws, tribe/caste based laws/tribunals, Jammu and Kashmir which until quite recently had its own seperate consitution and for example Indians from other regions weren't allowed to buy land or property there.)