What is the difference between Position and Offset on an oscilloscope?

To answer this first you need to understand the layout of how your waveform trace is displayed.

On your oscilloscope you generally will see either 8 or 10 divisions vertically on the screen.

Along the left side of the screen you will see a marker which indicates your channels 0V level.

You can move the position of the channels 0 Voltage indicator vertically anywhere on the display.

If the signal you are probing has a voltage offset; you can compensate for the offset by applying a voltage in the scopes offset menu.