lavatory 同 toilet 有咩分別 ??

Toilet is commonly used in Hong Kong.
Lavatory is usually used on transportation vehicle, such as: aircrafts and in U.S.A.
Washroom is used in Canada.
Bathroom is also used in both Canada and U.S.A.

Sometimes you might even hear people say:
Powder Room -- usually used by ladies.
John -- mostly used by men.

They all have the same meaning.

toilet 馬桶/廁所, 為英式用法
lavatory為盥洗室/廁所, 多用在飛機上

其實一樣，廁所!