Subtracting opposed dice in Anydice


In some games, opposed dice rolls are subtracted. An example (although this is a boardgame, not an rpg) is Twilight Struggle. Not only is it important to determine who won, but by how much. A similar situation would be when the DM creates a mechanic where opposed skill checks on say d20s are compared (who won by the most). I’m wondering how to do this in anyDice.

What is an easy way of doing this in anyDice?