on/by the bus

English as a Second Language English Vocabulary, Grammar and Idioms
1

“She’ll be arriving on/by the next bus.”
Could you tell me which is the apt preposition in the above sentence?

2

on

3

Mr. Alan.
Do you agree with Bleysin?

4

Well, I do.

She’ll be arriving on the next bus (specific)
or
She’ll be arriving by bus (as opposed to by any other means of transport)