My jeep doesn't have a remote start. But there is a big difference between an engine block heater and a remote start. All a remote start does is keep you inside your warm house and allow you to start you vehicle without going out in the cold. It still takes the normal amount of time for your engine to heat up and blow hot air out of the vents.
An engine block heater installs in the side of the motor and heats up the coolant in the engine so right away when you start the vehicle the heater blows hot air. It's a nice addition if you like up north like me.