this is a list of what i mostly saw in videos and screenshots. idk if i got every single thing thats going to be available and please add anything that i might have missed.
Armor abilities: thruster pack, jet pack, hologram, hardlight shield
power ups: active camo, over shield, speed boost (available in ordanance drops on infinity slayer, maybe classic slayer as pick ups)
specializations: AA Efficiency, mobility, firepower, ammo pack, resupply grenades, awareness, sensor
basically infinity slayer is going to have armor abilities and specializations in the loadouts. one power up in the random weapon drops along with two power weapons to pick from once meter is filled with kills and assists. classic slayer with loadouts might have classic halo with power up and power weapon pickups.