NEST THERMOSTAT COMPATIBILITY CHECK

[THOUFIQ6]

I have 2 types of AC units in my home.

The following terminals are connected,

Thermostat Type 1: Y, S1, S2, Hi, Med, Low, L, N

Thermostat Type 2: Y2, R, Y/Y1, G, B

Please let me know the suitable thermostat from Nest.

[CoolingWizard]

@THOUFIQ6, your Type 1 thermostat has an N terminal which I do not recognize.  Perhaps you can find a make and model number of that thermostat.  
Night or thermostat appears to have heat since there’s no wires attached to any W type terminals. 
In order to support three fan speeds you will need a Nest Learning Thermostat.

Your type two thermostat has a two stage compressor. That’s why you have a Y1 and a Y2 wire. Again this thermostat will need to be a Nest. Learning thermostat to support two stages of cooling.

AC Cooling Wizard