All the religious commandments do not have equal weight. What is given in the Qur'an in clear words,is Fard and what is stressed by the Prophet (PBUH) in a clear expression is Wajib. The way adopted by the Prophet (PBUH) himself is called the Sunnah and an action liked and desired in Islam is called Mustahabb.
Whatsoever is allowed and is not forbidden is called Mubah. To raise any Mubah to the level of Mustahabb is an innovation(bidat). No Mustahabb can be raised to the level of Wajib. On the negative side, strictly forbidden is called Haram, and forbidden is known as Makrooh-e-Tahrimi. Makrooh-e-Tanzihi means not desired and the last degree is Khilaf-e-Aula (not preffered)