To get on a bus,train,ship

Get on : bus,train,plane,ship,bicycle

- When they saw me, they got on their bikes and rode off quickly.
- My father will get on the plane at 7'oclock.
- You can get on this bus to go to the down town.

Get in/into: small vehicle : car,boat

- They got in a taxi and went to my work immediately.
- Yesterday when I was getting into a boat, I almost fell off the river.

Board:(formal) train,plane,ship,boat

- At London airport, we boarded a plane to Australia.
- A week later a bounded a ship bound for NewYork.

On board: train,plane, ship

- A light plane with four people on board crashed last night.
- They will get on board the ship at eight o'clock tomorrow.
- Smoking is not permitted on board aircraft nor other public transport.

Aboard: train,ship,plane.

- Reporters were not allowed to go aboard.
- Ships with unfurled sails wait to take them aboard.
- He was aboard an aircraft which took cereal,drug and cooking oil to London yesterday.
- He fled the country aboard a US Air Force plane.
- It has taken two hours to load all the people aboard.
- Nobody is allowed aboard the plane without a security check.
- The boat swayed as he stepped aboard.
- She invited 750 people aboard a luxury ship.

Notice that a board and on board are adverb and can be associated with verbs such as:get,go,come,step,take and etc.

Learner's common errors
1-Don't use of after on board you cannot say: They are on board of the plane.

2-It is wrong to use into after board: The pupils boarded into the bus.

3-When writing the word on board ,notice the space between on and board:onboard is incorrect.

4-You can use ON for on board or aboard in many contexts:
While I was on board/aboard the plane, I slept.= While I was on the plane, I slept.

5-To call everyone to get on the ship/bus you say : All on board
When you want to say that we can depart now, everyone is on the ship, you say : All are on board

6-You can use be,go,get with aboard,the more common colloquial form is the first:
- I've never been aboard a canoe.
- I've never gone aboard a canoe.
- I've never gotten aboard a canoe.

Mount: Bicycle,horse

- She mounted her horse and rode off/away.
- A man in a crash helmet was mounting a motorbike.

Embark: ( formal) ship

- I saw her embarking the ship.
- We embarked at Liverpool for New York.