Managing Large Conference Sub-Programs in CiviCRM
CiviEvent works marvellously for conferences. As Erik suggests use different roles for your delegates, speakers etc. From Civi help: "Participant Role:
The Role you select here is automatically assigned to people when they register online for this event (usually the default 'Attendee' role). You can also allow people to choose a Role by creating a Profile with the Participant Role field. Then include that Profile when you configure the Online Registration page for this event.