区别就是两者都是名词fire+不同名词短语，但意思是一样的。两者可以瓦换。
fire engine中文意思是消防车
The fire engine can carry extra tanks or refilling equipment， and a firefighter spends a limited time in the burning building.
fire truck中文意思是救火车消防车（等于 fire engine）
I could hook up another ambulance， a taxicab， a police car and a fire truck.
