In מסכת אבות ה:יז, we read:

כל מחלוקת שהיא לשם שמים סופה להתקיים ושאינה לשם שמים אין סופה להתקיים איזו היא מחלוקת שהיא לשם שמים זו מחלוקת הלל ושמאי ושאינה לשם שמים זו מחלוקת קרח וכל עדתו:

The traditional explanation of מחלוקת is an argument or dispute, which is the general Talmudic sense of the word.  However, some have suggested (I don’t have a reference, but this was first pointed out to me by Amram Tropper) that it does not mean an argument, but rather refers to divisions into separate groups of people.  In that sense, מחלוקת הלל ושמאי does not refer to their arguments, but to the fact that they separated themselves into different groups.  As long as this is לשם שמים, this is a good thing, but if it is not, like קרח וכל עדתו, then it is a bad thing.

This interpretation is supported by מחלוקת קרח וכל עדתו.  They are a single “division” against Moses and Aaron.  There is no know dispute BETWEEN קרח and כל עדתו.

This is further supported by the usage of the word מחלקת in תנ”ך. where it appears almost two dozen times, mostly in I Chronicles in lists of the divisions of כהנים and לוים.  Clearly here it does not refer to arguments or disputes among them, but only to their being divided into different groups.

(This post can also be found in the Mishnah blog)