I think there are a couple of issues:
1. what has already been said about the training - you train the different variables so thay you may use either in a fight. if you can kick high, then you can easily kick low, but the reverse is not true. the same goes for stances.
2. longfist is used as a basic style by many, meaning they have training in other styles also. they may blend what they find useful in their other styles into their longfist.
3. modern wushu has had a great influence on longfist in recent years, and some schools may tend to focus more on wushu (I'm guessing at this one)
4. personal preference. For example, from what I hear, there is a verson of gong li chuan that emphasizes grappling. also from what I hear, the ymaa version advocates striking.
i'm nobody...i'm nobody. i'm a tramp, a bum, a hobo... a boxcar and a jug of wine... but i'm a straight razor if you get to close to me.
-Charles Manson
I will punch, kick, choke, throw or joint manipulate any nationality equally without predjudice.
- Shonie Carter