Showing: a buyer's agent requests a viewing on the listing page. The listing agent approves, declines or proposes another time. After the visit the buyer's agent gets a short feedback form (interest and opinion on the price), which the listing agent sees.
Open house: a public viewing day. Anyone can register (RSVP) on the listing page and receives a confirmation email.
Broker open: a viewing for agents only. It is visible to members, not to the public, and members register in one click.
Schedule them from your listing page. See all events and guest lists in Listings → Open houses & events.