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Nobody says it anymore
(startrek.website)
I've heard it explained that "hey" used to be more of an urgent way to get someone's attention, rather than a casual "hello" like it is now, so it sounded rude to some older folks.
Not an important difference, no.
Your feelings are valid and real. But as a society, the new standard is that there's no difference. If you decide to catch up, it will lead to much fewer hurt emotions.