Thread:TheFlash700/@comment-3096633-20150108025402/@comment-34326521-20150108130239

"Here's this thing you didn't know about that was just created. Now that you know about it thanks to this unwarranted message, please join."

That's advertising (and it's what you did).

"Here's this event you already knew about that I want you to attend, since you're my friend/co-worker/family member and I'd like to hang out with you."

That's an invitation (and it's what you didn't do).