Perspective?

• I’m promoting something.
• You’re advertising at me.

There is a connotational difference, but it’s pretty minor. By definition they’re synonyms. Advertise has a more organized corporate vibe, like there’s an underlying implication that there’s money involved. Promote can be more personal.

“Advertise” to me implies a commercial purpose. So for a Lemmy community “promote” sounds more appropriate IMO.

Advertise with commercial intent. Promote with personal intent.

I’d say it’s advertising if money is involved, promoting if it’s not.

If you paid for the promotion to be mentioned or displayed, then it is an advertisement.

The two words are spelled differently.