It's a method of navigating the human experience of social interactions to avoid offending and embarrassing yourself and others. Tradition is a whole other ballgame and can be changed at a whim. As long as we have fellow humans to interact with, etiquette will always exist, like it or not. Being in a pandemic doesn't give free rein to act any way you want. If anything, etiquette is needed now more than ever.
Examples of both:
Tradition: most wedding traditions stem from prehistoric(Biblical)/medieval times. The veil also associated with not seeing the groom before the ceremony, matching bridesmaids, father giving away bride as property, bride stands on groom's left, and so on depending on the culture/family/social circle. Many of these still exist but the meanings have been long forgotten and people do them because they're expected with no understanding why or they eliminate them entirely.
Etiquette: sending prompt thank yous, being gracious hosts and guests and everything that entails, making sure the entire group is treated equally and not upset or offended instead of letting things slide for select others, amending behavior when it is pointed out as rude. The list goes on. It does not change because someone thinks it's outdated.
So in the end they are not the same or interchangeable