No. The Nest is designed to run with or without a C-wire. The Honeywell thermostat (Model: RTH9585WF) is designed to use the C-wire or an alternative installation using the G-wire, if the C-wire is not present. So the two thermostat's wire configurations are not necessarily the same, but depending on your situation, you may be able to use this thermostat if all you're missing is the C-wire, but you have a G-wire to use in its place. The G-wire normally controls the operation of the system’s fan, but if it's used as a substitute for the C-wire, then the fan can no longer be used independently. What this means is that the fan will only turn on/off when the air conditioning or heater is running. If you never run the fan independently, then this won’t be a problem. If you would like to maintain that functionality, then an electrician will need to install a C-wire on your system. Honeywell’s website provides a lot of information and videos regarding this and other installation topics. Good luck!