Both are South Asian movements that emerged in the nineteenth century, and both are broadly Hanafi in fiqh and Maturidi in creed with a Sufi orientation, so their dispute is largely over practice rather than the pillars of belief. The Deobandi school tends to be more reformist and stricter against practices it regards as innovation, while the Barelvi school gives greater emphasis to celebrating the Prophet's birth, seeking intercession, and venerating saints and their shrines. Ahl al-Sunnah weighs any such practice against the texts, since the Prophet ﷺ said, "Whoever introduces into this affair of ours something that is not from it will have it rejected," and warned, "Do not exaggerate in praising me as the Christians exaggerated about the son of Maryam" — while still refraining from takfir of the ordinary Muslims within either group.
Q&A · Sects & Comparative Belief
What is the difference between Barelvis and Deobandis?
Evidence — the daleel
Sahih al-Bukhari 2697 ṢaḥīḥSahih Muslim 1718 ṢaḥīḥSahih al-Bukhari 3445 Ṣaḥīḥ
On deen2u
Informational, not a personal fatwa. Consult a qualified scholar for rulings on your situation.