Not sure how cemeteries are maintained. In the US maintenance is handled by a religious or private organization. They are usually fund via burials fees. These organizations can run out of money if the cemetery is full or religious entity closes for some reason.
Updated values including maintenance org closure:
full: all the plots are occupied and the cemetery is open and being maintained
disused: no burials happening because maintenance organization has ceased functioning.
removed: bodies and statuary moved to storage or another cemetery.
abandoned: cemetery is no longer accepting burials or receives active maintenance. Periodic maintenance by private citizens is preventing the land from being overgrown.
ruin: cemetery has been neglected for so long that headstones and statuary have started falling down and the land is reverting back the nature state for the region.