Typically similar deals are for carryout only. For example Domino's has an ongoing deal for $7.99 large, 3-topping pizzas but only for carryout orders. Pizza Hut looks to emphasis that fact by calling their deal the "#1 Pizza Delivery Deal."
The promotion is only good on orders placed online. You can also upgrade to a large specialty pizza for $3 more (i.e. for $10.99).
Photo via Pizza Hut.