In The Name of Allaah, The Most Merciful, The Bestower of Mercy.
There is no Inkaar [disapproval of one another] in those affairs about which the (scholars) hold differences of opinion!
Some people are under the illusion that what is intended by this statement is that it is not permissible to disapprove of (one another) with regards to any affair in which difference of opinion is held; so based upon this (illusion of theirs), it becomes impermissible to disapprove of a Munkar (an evil) unless there is complete agreement in doing so. This is a wrong understanding necessitating the closure of the door of enjoining good and forbidding evil. The scholars hold differences of opinion in most of the masaa’il and that which is correct with regards to this statement “Laa Inkaar Fee Masaa’il Al-Khilaaf” is that there should neither be harshness in disapproval nor reprimand with regards to those issues about which there is no manifest proof to be taken as the final (affair). And the basis upon which this is founded is that the issues of khilaaf are of two categories:
The First Category: They are those issues about which there is proof necessitating that it be taken as the final (decision); so here the proof must be taken and the other statement (opinion) in opposition is discarded. And whoever follows the statement (opinion) that is established to be in opposition to the proofs, then he is shown disapproval (i.e. clearly stated to him that what he holds is wrong without going into excess).
The Second Category: It is those issues of khilaaf about which the proof has not been manifested for it to be taken as the final (decision). It is an affair in which the evidences are either at contention or the views are at variance. This is an issue of ijtihaad, and there is neither disapproval nor reprimand against the one in opposition; rather advice is given for acquaintance with the statement (opinion) that carries more weight. This second category of (khilaaf) is what is intended by the statement Laa Inkaar Fee Masaa-il Al-Khilaaf), which some people have understood in an unrestrictive manner.  [See Footnote A about Hairsyles]
The Khilaaf of Ahlul Bidah
Al-Allaamah Rabee Bin Haadee Al Madkhalee [may Allaah have mercy upon him] said, “We do not say that there are people of ijtihaad amongst ahlul bidah because they are followers of desires, and Allaah and His Messenger have testified to this. The misguided innovator stirs up discord and errs, and then says to you, ‘This is ijtihaad’. And when Hikmatiyaar and the misguided parties (in Afghanistaan) murdered Shaikh Jameel Ur-Rahmaan, they said, ‘This is ijtihaad’. Making lawful the spilling of the blood of the Salafis is ijtihaad to them! This is what it is, they (ahlul bidah) do not fall upon an affair of misguidance or a calamity except that they say, ‘This is ijtihaad’. This is a dilution of Islaam, mixing falsehood, misguidance and bidah with truth when the mistakes of the (real scholars of ijtihaad) for which they are rewarded are placed at the same level with religious innovation about which the Messenger [sallal-laahu-alayhi-wasallam] has informed us that it leads to the fire”. 
Footnote A: We keep on hearing some youth talking about Khilaaf regarding a particular hair style! Read here by Shaikh Abu Khadeejah [may Allaah preserve him]: https://www.abukhadeejah.com/the-prohibition-of-qaza-hairstyle-disallowed-by-allahs-messenger/
 Ibaaraat Moohimah. page:25
 Ajwibatul Allaamatush Shaikh Rabee Bin Haadee Al Madkhalee Alaa As-ilah Abee Rawaaha Al-Manhajiyyah. page: 20