Originally Posted by
ernestnywang
I understood what you mean; YR/YQ is the only thing that could be different. There are some very rare occasions where an airport's tax is raised and requires airline to collect the new amount if the ticket is ever reissued, but other than that, if no ticketed points and O/X are changed, taxes other than YR/YQ should not be any different.
In Europe at least, many airport fees and government taxes are contingent on whether it is O or X. And indeed UK's APD can vary on time of day between arrival and departure if domestic flights are involved.