What is the difference between theatre and classroom seating?

Theatre

Chairs in rows, no tables. Highest capacity, no writing surface. Use for plenaries and presentations.

Classroom

Rows of tables with chairs facing front. Roughly 30–35% fewer people than theatre in the same room, but delegates can take notes and use laptops.

Banquet

Round tables, usually 8–10 per table. Used for dinners and galas.

U-shape

Tables in a U, everyone facing in. Small groups, discussion format.

Boardroom

One closed table. Smallest capacity.

Worked example — Conrad Ballroom, 963 m²:

950 theatre → 650 classroom → 750 banquet → 160 U-shape → 146 boardroom.

Same room, five very different numbers. This is why a single "capacity" figure is not enough to plan an event.