Depend on the situation, the word "ship" mostly will be use in the trading process, like if you buy a cellphone from a store, they will ship it to you

Both "send" and "ship" can be used interchangeably in the context of a mail service. However, there are some differences between these two words in a general context. Think of the word "send" as meaning to take something from point "A" to point "B." "Ship," however, implies that some sort of vehicle is being used, such as a car, truck, boat, airplane, etc.