问“long before 与 before long”有什么区别?

问题描述:

问“long before 与 before long”有什么区别?

例句:
The house was burnt to ash long before the fire fighters came.
The house was set on fire.Before long,it was burnt to ash.
第一句before long表示在消防队员赶到以前房子早就被烧成灰烬了
第二句before long就是过了没多久
可以理解吗?