What is the difference between Salafism and Wahhabism?
(As I know they are different from Sunnis. So what is their opinions?)
بسم الله الرحمن الرحیم
Muhammad Husayn Ibrahimi defines Wahhabism in his "A New Analysis of Wahhabi Doctrines" as such:
Wahhabism has been labeled with many various names among which is the appellation, ”Salafiyyah”. This name is used because they believe that for the reformation of their religion and beliefs, the present Muslims must go back to the early period of Islam (”Salaf” means the past or preceding one). Ibn Taymiyyah has introduced the issue of”Salaf” and his statements are a source of Wahhabi doctrines.
By “Wahhabism” it means that Shaykh Muhammad ibn 'Abd al-Wahhab must be followed in socio-political and religious issues because he has taught his followers the way to reform religion and society.
Muhammad al-Tijani al-Samawi also has explained this issue in his "The Shi'ah are the real Ahlul-Sunnah":
These are members of the largest Muslim community; they represent three-quarters of the total population of the Muslims of the world, and they are the ones who refer for religious verdicts (fatawa) and for religious following of the Imams of the four sects, namely Abu Hanifah, Malik, al-Shafi`i, and Ahmad ibn Hanbal.
Later in time, those called Salafis branched out of them; the characteristics of their beliefs were later revived by Ibn Taymiyyah whom they call “the one who revived the Sunnah,” then by the Wahhabis whose ideology was invented by Muhammad ibn Abd al-Wahhab; theirs is the sect of the present rulers of Saudi Arabia.
Many scholars believe that Wahhabism is a sect of Salafism. Muhammad al-Tijani al-Samawi says in his "All Solutions are with the Prophet’s Progeny":
It is worth mentioning to say that the deeds of the Prophet’s companions are an argument against the Wahabis, because they believe that all the companions are totally just and honest. They claim that they follow them. They call themselves as Salafis meaning that they follow the “pious ancients” and that all the companions were pious and righteous in their view.
Salafism is more of an ideology - and sometimes a movement - rather than a denomination. The basic idea is that the first society ("Aslaaf") established by the Prophet of Islam (puh) himself was exemplary and as such mimicking its qualities is tantamount to "returning to true essence of Islam." Outside polemics, there is no such claim that each and every member of the society was par excellence, but rather that the collective "righteousness quotient" (RQ) of the forebears was par excellence. The scope of Aslaaf varies but is generally limited - in the light of Ahadith - to first three generations of Islam.
The Salafi idea can have different interpretations, i.e. what to look for in Aslaaf and how to apply that to present times. Consequently, there is literalist Salafism, which puts more emphasis on a literal reading of the scriptures and early culture and replicating their practices. In opposition, progressive Salafism (al-salafia al-taqaddumiyya) - also neo-Salafism - is found in Modernists and differs as they understand the early society in the light of Modern ideas and posit a "returning to the true essence of Islam," by replicating the thinking of Aslaaf not practices.
Another class in Salafis is Quietists, which focuses on scholarly reforms as compared to political activism. As always, in reality, a spectrum between the opposing poles exists.
Corollary: As an ideology Salafism is not orthogonal to a sect, in particular Ahl-ul-Sunna. As a matter of fact, on close inspection, the core ideas of Salafism emerge in different, often strange, contexts. Personally, I find the core precepts of moral Sufism to be a call to "return to the spiritual moral purity of Aslaaf," i.e. Spiritual Salafism.
Corollary: In regular usage, Salafism can only be understood with reference to the "problems" that are seen and therefore the "solutions" that are posited to "return" to the true spirit of Islam.
Wahhabism is a realization of the literalist non-Quietist blend of Salafism - as a movement - who see moral decline, corruption of Creed, shutting down of Ijtihad and innovations as degeneration from Aslaaf. (None of these were newly discovered by the founder of Wahhabism) In the beginning the solution found was solely active religious reform but eventually engulfed political activism by forming a politico-religious alliance with Al-Saud (the ruling monarchs of Saudi Arabia). This alliance may be considered as the true defining moment of Wahhabism for later times.
There is no difference between any of them. As for Wahhabism or Al Wahabiyah, it is attributed to Muhammad bin Abdul Wahhab, this name is not a name that it's followers call rather it is name which was coined by those who were against it. As for the Salafiyah it is a methodology which follows the Salafussalih, and there is no difference with what is known as Sunni.
So there is no difference among them, and I will not go into details as the answer would be quite long. In the end the point is in not the names but in what they follow and mean.
You stated that "they are different from Sunnis", that's not true at all, Sunnis follow four schools of thought, what people call "Wahhabi" or "Salafi" also follow these four schools of thought.
"Wahhabi" is actually a derogatory term for a "Salafi" so let me end its use now.
The above being said, if Salafi and Sunni is the same, then why have they been categorized separately?
I can give you an example that will help you understand, consider the term "Islamist", an Islamist is a Sunni, the Islamist follows one of the four Sunni schools of thought, just like a Salafi, but an Islamist is put in a separate category, why? An Islamist is a Sunni, but what is the difference between a none Islamist Sunni and an Islamist Sunni?
What is the difference between a Salafi Sunni and a none Salafi Sunni?
There's none, a Sunni follows the four schools of thought, a Salafi Sunni follows the four schools of thought, the Islamist Sunni follows the four schools of thought:
The answer you chose makes false accusations against Sunnis who are categorized as Salafis, for example saying: "they believe that all the companions are totally just and honest", this is a false statement quoted from a person who is a Shia.
Salafis don't believe all prophet's companions are "totally just and honest", rather they believe the prophet's companions are the best of men.
They didn't invent this, they got this from a Hadith, that's why they're "Sunni", because they follow the Sunnah and teachings of the prophet:
"The best of men are my generation, then those who come next to them, then those who come next to them. Afterwards people will come who will give testimony before swearing an oath, and swear an oath before giving testimony." (Bukhari and Muslim)
The above Hadith refers to the Sahabah, and this is why Sunnis not only respect but also trust the Sahabah, because as the prophet said, they're the best of men.
Hanbali is one of the Sunni Schools of thought, Hanbali derives its decrees from Quran and Sunnah, and also considers the opinions of the Sahabah.
The above being mentioned, why aren't Salafis called Hanabli instead?