Playstyle of Dark angel

DK Beginner here. I just start collecting and playing for 2 months and have been enjoy it so far. However I got a little problem of how should I play my DK army. I have watched some videos but so far I dont see how I should play DK differently from othr space marine. I just put a couple of deathwing knight, azrael, and played it like how I would play Ultramarine just with DK specific units since I also use Gladius.

Am I playing it correctly or there are specific play style for DK? Right now it feel like I play "Ultramarine" but 1 deatgwing knight and thats it. I only got one group of deathwing knight as well so that probably the problem?

Thanks and sry for my English