>>39759000Yuri/yaoi shippers keep things civil, hide overly shippy art, don't push things onto chuubas, and most importantly they focus on shipping the characters. They also usually genuinely like both parties involved and their interactions so they try not to do anything that would make them awkward (or eventually stop interacting).
Hetniggers usually like a ship either because they want to annoy a certain fanbase (unicorns, fujos, /u/fags), they unironically want to push cuckshit for fetish or whatever reasons, or so they can have one of the chuubas in the ship become an accessory for the other. They also focus on the people behind the characters, talk about how they're dating, and they push their ship so much to the point that it makes the chuubas themselves uncomfortable. Nobody wants to appeal to those fans.