Hello
In my understanding, here in the UK there are generally 3 basic trims - ES, SE and M-sport. I guess everyone is familiar with the M-Sport now.
ES = Edition Sport (not to be confused with "M Sport")
SE = Special Equipment. Some also call it Special Edition but I dont think there's anything special about it
The SE has much better equipment than the ES and is worth a lot more because more people want them.
The ES is generally a cheaper BMW, but does not gain much interest when you want to sell it.
I'd go for the SE over the ES but given the choice would go for the M Sport every time.
In terms of hierarchy, it goes like
1. ES (Cheap, less equipment)
2. SE
3. M-sport (Most expensive, lots of equipment)
There might be also a basic model not included in this hierarchy.
Correct me if I'm wrong =)