Here a sort of summary of the differences between the two hat boards. Both boards use the same software, the difference is the hardware setting which can be set using the Web interface.

Here the summary few words:

The irrigation hat supports up to 12 relays connections and has 8 physical button that can be configured to activate the relays, it is useful to provide easy and quick access to the relays activation in case you often use manually controlled irrigation and not only the scheduled. It also supports automation functions but the Analog sensors cannot be supported. Everything should be native digital.

The automation/irrigation hat supports up to 16 relays connections, does not have buttons, but it has several physical interfaces. In particular it has an analog to digital converter (0-5v) that can be used to interface analog sensors (including capacitive hygrometers, etc). Later version of the board has also an analog input which ranges from 0 to 15v which can be useful to monitor batteries in case of solar powered systems.

Both boards have interfaces for digital sensors (air temperature, air humidity and light) as described in the hardware page of the site.

Both boards can be connected to same type of relays, the relays can be used to control not only the valves but pumps, lights, fans, heaters, etc. (within the power and voltage range of the relays) Always recommend to double check the specs on the Tindie shop page as some of the features might change over time. (https://www.tindie.com/stores/angelova/) Regards, Angelo