How much "Deobandi" someone is is determined by how closely he follows what the akabireen of Deoband did. If a Deobandi decides to take part in hadra, then he is not representing Deobandis. If a Deobandi organizes mawlid celebrations or approves of them, then he is not representing Deobandis. Those who stick to what the akabireen have taught, he is a true Deobandi. The differences that exist amongst Deobandis are differences you'll find amongst non-Deobandi (and even non-Salafi) scholars as well.