Mathhabs arrise due to different interpretations of the Quran, Sunnah and for political reasons. The word mathhab and sect can be thought of in the same way usually, but there is a difference because there can be different mathhabs within the same sect. Examples of Mathhabs include Shia, Sunni, wahabi, salafi, deobandi etc. A muslim should not follow a mathhab when it contradicts clear proof in the Quran and Sunnah.