Having just re-read my original post, I don't think I explained the Primary Key bit very well, and I don't want to send you off in the wrong direction because of a bad explanation from me.

The point I intended to make was that if you identify Event type A using different columns from Event type B (e.g. If the primary key for Event type A was the Event Name, but for Event Type B it was Date and Location), they ought to be separate tables. However, if all Event types were identified by their Event Name, and these were unique regardless of the event type, then you could consider using a single table.