The correct unit to describe the distance between stars is the "light year", the distance a photon of light would travel (through a vacuum) in a year.
Light year or astronomical units
you use light years, and other units
The distance between two stars is typically much greater than the distance between two planets. Stars are usually light-years apart, while planets in the same star system are typically within a few astronomical units of each other.
light years
A distance in space, between stars etc.
The distance between the points of (4, 3) and (0, 3) is 4 units
The units currently used for distance between stars are either light-years, or parsecs. If the stars are very close together (as in a binary system), AU might also be used.
The distance between stars can be anything from light minutes to billions of light years.
Stars are not measured in light years. The distance between them is.
69 units
Just subtract the lowest number from the greatest number. For example, the distance between 3 and 8, is 8 - 3 = 5 units, the distance between -2 and 3, is 3 - (-2) = 3 + 2 = 5 units, the distance between -4 and -2, is -2 - (-4) = -2 + 4 = 2 units.
They do not use units: they use the fact that stars are not galaxies. For example, you don't use units to measure the difference between children and countries.