Pull up and Pull Down refer to pulling a signal up to a reference voltage, and pulling down refers to pulling a signal to ground. Each has different wiring because they are on opposite sides of the switch. That’s why you have been asked for your schematic/wiring diagram.
On the Jetson Nano, like the Raspberry Pi, there are built in Pull up and Pull down resistors which internalize the actual resistor itself. On the Raspberry Pi, the direction (pull up, pull down) are programmable in user space, on the Jetson Nano they are setup in the device tree and not easily accessible at run time. Therefore you need to pick your method and wire the switch accordingly.
As we talked about before, wired and programmed properly you probably don’t need to add an external resistor on a properly selected pin. However, for people who might make a mistake and program the pin as output instead of input ( I believe most programmers have been guilty of this sometime in their career), or select the wrong pull up/pull down, an extra external resistor is added so it doesn’t short out the pin.
Here’s a good explanation of the pull up/pull down concept on the RPI:
From the video, the 10K Ω R1 resistor is the one that we are talking about as the built-in 100K Ω resistor of the Jetson. It’s built in to the board, you don’t need to add it externally. The R2 1K Ω resistor is the protector resistor we’ve been talking about. The value is probably a little high for the Jetson, you may have to lower it in application.