the conductor is the most important; the porter is only an assistant
A person is not required to tip a conductor on a train. Amtrak doesn't discourage tips, but advises customers that tips are not required for either the attendants or the conductor of the train.
That would be a conductor.
The porter is at the front of the train.
In America that's the conductor.
When you come aboard a train, you are greeted by a wo/man who collects you tickets. Who is this person, you wonder? S/he is the Conductor! The Conductor is responsible for collecting tickets and in charge of the train. Not necessarily the wo/man who keeps the train running.
in the porter closet
In the dining cart, near the back of the train, the porter should look like you.
In the back of the train
Please have your ticket ready when the conductor comes along.
You didn't say which meaning of the word you want to be used. A conductor can be the person who sells and checks tickets on a train. A conductor can lead the orchestra. A conductor can be a substance that will carry electricity. There are also many other meanings. Here are a few sample sentences.I handed my ticket to the train conductor.The conductor gave the beat, and the orchestra started playing.Gold is an excellent conductor.
a train conductor minds the train whilst a teacher trains the mind.
A Conductor.