A slot is a slot, when talking about movements in and out of the major cities... You can send an A380 or a SAAB340, it doesn't matter.
There was a deal made between the Agrarian Socialist Party and the government at the time about protecting the regional slots in prime movement time at Sydney airport so that country folk could access the city in one day without having to overnight. ie down first thing in the morning then back same night. Part of the deal was those slots could only be used by regionals.