There are a few different variables that make the “style”. For instance, there is the dynamic start vs static start| starting hip/ back angles| hip/back angle at the hip | if you are making contact/ where is the contact if there is| weight distribution through the lift| catapult/triple extension | etc.
The easiest to probably to see is start type:
Static start: Hossein Rezazadeh
Dynamic start explained by Catalyst Athletics
This podcast does a pretty good job talking about the differences between the catapult/triple extension techniques.
When referring to technique styles like Chinese, Bulgarian, etc. a great deal of difference is probably due to the different coaching styles and the different anthropometrics. For instance, the top Russians seems to be of higher weight classes, where Chinese seem to be lower to mid weight classes. For instance, Klokov is 6’ vs Lü is 5’8’’. Even if they had the same coach their style would likely still be different due to the difference in their sizes.
Regardless, your style should be what allows you to lift the most weight or develop the muscle/motor pattern needed for another sport. For instance, if you are an Olympic Weightlifter and you can power clean more then what you can clean, your competition style should be a power clean. On the other hand, if you play football or rugby, your style maybe power cleans since you may be more interested in developing your triple extensions and not interested in maximizing your clean.