It mean mostly that they would fight for a nail or a tooth not much different so they would mind who it was.
Romeo doesn't want Juliet to be associated with the moon because the moon is less beautiful than the sun.
In fact, Romeo compares Juliet to the sun because she is out of his reach, very bright and beautiful, and is like the sun that guides him.
Boiling point. Distillation is the process of removing one substance from another by boiling it away. This is possible because of differences in boiling points of two substances.
