With or without the ESP turned off you will be able to tell because as soon as you pull away from a standing start the car will not bog down. This is because all four wheels are trying to get the car going.

Front wheel drive - front wheels pull the car along, the rear end moves down and then the car moves

Four wheel drive - the front wheels pull, the rear wheels push and the car sits level while accelerating.

You should be able to tell by looking under the rear, a 4wd car will have a drive shaft and a Slip Diff which looks big and round in line with the rear wheels.

Look at any Scooby and you'll see one.

Hope this helps.