I've spent more time than I want to admit trying to figure this out. Posting here for others who may have the same question. I'll be as brief as possible. The descriptions listed below include "max" capabilities and in each you may need to purchase additional modules to get to the number listed.
AquaRite S3: Salt system only.
AquaRite S3 Omni: Salt system + Omnihub Automation. Uses OmniLogic app.
OmniLogic App: App used to control everything remotely. Software. Not to be confused with OmniLogic Hardware. The app can be used across multiple hardware products.
Omnihub (Control): The product you can use to retrofit automation into an existing system. No breakers in unit. If you want to add this to an S3 system after the fact, this is the model number: AQRS3OMNIKIT. Lowest system in the automation tiers. Controls 4 bodies of water (pool, spa, etc.), 3 variable pumps, 2 actuators, 1 heater + 1 solar, 3 high voltage relays (lights, booster pump, etc.), 1 low voltage relay, can add AquaRite for chlorination, built in wifi.
OmniPL (Control): Automation system that has breakers in the unit. Has fewer high voltage and low voltage relays than OmniLogic Automation Panel (hardware) and more than Omnihub (Control). Middle system in their automation tiers. Controls 3 bodies of water (pool, spa, etc.), 8 variable pumps, 4 actuators, 2 heater + 1 solar, 8 high voltage relays (lights, booster pump, etc.), 2 low voltage relay, comes ready for salt chlorination, 8 breakers in panel, built in wifi.
OmniLogic (Control): Automation system that has breakers in the unit. Most high/low voltage capability. Top system in their automation tiers. Controls 4 bodies of water (pool, spa, etc.), 16 variable pumps, 4 and expandable up to 8 actuators, up to 5 heaters, includes 4 and expandable to 10 high voltage relays (lights, booster pump, etc.), 4 expandable to 8 low voltage relays, comes ready for salt chlorination, 12 breakers in panel, need to add wifi.
The ProLogic automation uses an AquaConnect software.