How is an AU different from a solar mass?
An AU is the distance from the black hole at the center of a galaxy to the closest planet, and a solar mass represents a measurement equal to the mass of a black hole's quasar
An AU is the smallest unit of measurement in quantum mechanics, and a solar mass is the largest unit of measurement in astronomy
An AU is the distance from the event horizon to the singularity of a black hole, and a solar mass is the distance between the two closest black holes in a galaxy.
An AU is the distance from Earth to the sun, and a solar mass represents a measurement equal to the mass of our sun.