Just ask an Aalim/hard core supporter of any group (in India pakistan Bangladesh most notably Deobandi/Barelvi/Salafi(Ahle Hadith) a simple question.
Question. What is the difference between your group and other group??.
Answer: The answer he will give that we have Aqeeda differences. He will say that our group is on the Aqeeda of Ahle sunnat Wal Jamaat and obviously the other one is deviated.As Aqeeda is most important for a muslim so any further deliberation stops because it looks that they have basic differences.

But the reality is totally different.
Too understand the real picture Lets know some important facts.
1.    While the differences of fiqh (Jurisprudence ) is right from the day of Sahaba, and this became further evident with the four school of Fiqh,and later development of  Ahle Hadith.
2.    There was no difference in the matter of Aqeeda among Sahaba .
3.    As aqeeda matter has been described in detail in various Ayats of quran and Ahadith of hazrat Muhammad Sallallahu Alaihi Wasallam. These six articles of belief has been described in clear words in Quranic Ayats and has been sum up in the Hadith of Jibraeel that is in Bukhari and Muslim shareef both.
4.    And all the salfussalihin and Four great Imams and Muhaddithin were having no difference in the matter of Aqeeda.
5.    The development of Ashari and Maturidi school of Aqeeda was out of necessity and not out of fun.
6.    Aqeeda Schools came into existence to deal with the deviated philosophical interpretation of quran and hadith and subsequent deviation that emerged after 300 Hijri with the rise of Muatazilla under the patronage of Mamoon and Muatasim of Abbasi Dynasty.

7.     Schools of Aqeedah among present day Sunni Muslim
There are only two surviving schools of Aqeedah among mainstream muslims. They are 
1.    Ashari and Maturidi School of Aqeedah
2.    Salafi school
These are only the surviving school of Aqeeda among sunnis all over the world.
8.    In matter of jurisprudence there are four school (hanfi,shafai,maliki,hanbli) plus Gair Muqallids but in Aqeeda only these two.
9.    The groups (namely Deobandi,Barelvi,kerala Sunnis AP and Ek) belong to Ashari/Maturidi School of Aqeedah while Salafi/Ahle Hadith/kerala Mujahids are of Athari/Salafi School.
10.                       Jamaat Islami and Tablighi Jamaat are basically Dawah movement and in principle do not involve in Aqeeda differences issue..(But it is perception is that Tabligh is synonymous to Deoband and Jamaat Islami is close to Ahle Hadith, but in reality this perception is not true.The individual member of Tabligh and JI may be closer to these in his personal capacity but on organization level they don’t have any proximity to any group.
11.                       The difference of  Ashari/Maturidi and Salafi/Athari are also not in principle.In principle is that muslim should believe the aqeeda as detailed in quran and Ahadith as explained by sahaba and great scholars and Imams of first few generation. and no philosophical and interpretational approach will be applied to explain it.They are dead against all the philosophical thought and logical interpretational approach of Muatazillah,Jehmiah and other Deviated group.  
12.                       Most of the differences that the different group claim between them are actually not of Aqeeda matter.But in public they are designated these differences as Aqeeda differences.
13.                       They differ only in some details of certain points. (These will be elaborated in discussion) 
14.                       Some of these differences are on those detail that were not considered important enough to be discussed by sahabah and scholars of knowledge. Sahabah asked from prophet detail of even small things of daily life if these Aqeedah detail would have been important for deen surely they would have asked,this sprit was followed by all the pious and knowledgable scholars of Salfussaliheen.
e.g One person came to Imam Malik and asked What is the EXPLANATION of Istawa Alal Arsh He replied ; Istawa is definite and kaifiat …….is not known. After that he asked the questioner to be chased away from his majlis and said he is spreading Fitnah.   (To be continued)