The big difference between what we have now with daily blood moons and horde mode is:
No zombie spawns at all during the day.
Small arena with multiple air drops in close proximity.
Themed airdrop crates for food, weapons, ammo, and building materials.
Horde mode was more about frantic building and defending. There was zero exploration, clearing POIs, and minimal gathering and crafting mats. The airdrops contained stacks of blocks ready to just be placed. The types of things you got also changed as days progressed. You’d start out getting wood blocks, spikes, and clubs and crossbows but then in following days get concrete blocks, machine guns, and mines.
The labeled crates that we have were taken from the old horde mode as those were the airdrop crates we would get and you could see at a glance what type of loot you would get.