Remember there are well over 50 "recognized" islamic brands in the world, and most of them consider the others as heretics worthy of instant death (if permitted by the local strongman).
Halal is standard dietary law. Different sects all follow it, when it comes to the slaughter of non-aquatic meat.
It’s like Kosher. Some liberal Jews disregard it, but the laws of Kosher do not change. This group is what the Muslims in my area (Detroit) use as a guide. It’s not about the different sects.