Are the leaves <1/2″ or >3/4″ wide?

Leaves mostly less than 1/2" wide
Fruit less than 1/4″ in diameter
Narrow-Leaf Peppermint (Eucalyptus nicholii)
Narrow-Leaf Peppermint (Eucalyptus nicholii)

Leaves mostly 3/4" wide or wider
Fruit 1/4″ in diameter or greater