Why is it 'på' here and not 'till'?
You can say till konferensen too.
What's the difference in meaning between the two? (på konferensen and till konferensen)
I don't think there is any difference here. Speakers might just prefer one or the other.
I think "på" is more involving. You can go "till" the conference and then leave but"på" is more like you really want to participate in the conference. Can someone confirm this?
Varför är "ska inte komma" accepterad?
Why is "åker" not accepted?