How to wire A/C Thermostat given different wiring conventions
It does not seem that the thermostats are compatible, no.  Your existing thermostat is designed to control a heat pump with a multispeed air handler:


L1/L2 are likely 24VAC in
COMP controls the heat pump compressor
R.V. controls the heat pump reversing valve
HIGH/MED/LOW control fan speeds
the unused wire is just that -- it looks like someone wired your 'stat with network cable BTW, which is a bit of a no-no.


The new thermostat you have is designed to control multispeed air handlers in zoned hot water (hydronic) systems instead -- instead of controlling a compressor and a two position reversing valve, they are designed to control a variable-position hydronic zone valve, typically for heating only as they have no heat/cool changeover system or extra outputs for controlling cooling components.