Could somebody please tell me the difference between "hello" and "bye"? "
An indirect question is not always wrong:
"I'd like to know the difference between "hello" and "bye".
At the unacceptable end is a subject line saying "hello and bye", with the message being "as per subject line".
Incidentally, some readers are irritated by having to keep referring to the subject line. All question content should be in the message. That is, it is not good form to write "hello and bye" in the subject line, and "What's the difference between these two words" as the message.
Other people don't like being thanked in advance, but I usually ignore it.
That's about it. I'm sure other people have different preferences.
Student or Learner