zusteigen vs einsteigen
Was genau is der Unterschied zwischen diese beide Wörter?
Zusteigen kind of implies that there are already other passengers, but the words are really used as synonyms.
Einsteigen is much more common. The only context zusteigen is regularly used, is the conductor´s question: Noch jemand zugestiegen? (Has anyone boarded the train at the last stop?)
Zusteigen and einsteigen can be used synonymously. So, if you are on a train it would be quite likely to hear either "Bitte zusteigen!" or "Bitte einsteigen!". The difference in meaning is very low. You would probably use "zusteigen" rather than "einsteigen" in a sentence like "Bitte machen Sie die Türen frei und lassen Sie die anderen Fahrgäste zusteigen" because the new passengers would be added to (zu) the old ones. Does that make any sense?