Queens move slowly except when on the creep due to their Creep Move ability, making "queen-rushing" difficult. Queens are much more powerful in overall combat ability on the creep. Its attack consist of spines launched by the "wings" on its back.
The queen tunnels deep underground, surfacing at a friendly target zerg building. The queen can effectively "teleport" underground to a friendly base. This ability can be used only while the queen is on the creep.
The queen used to spawn numerous types of structures upon the creep. Creep does not belong to any one player, which gave the queen the ability to spawn structures upon "enemy" creep in enemy bases. This ability has since been lost.
When the queen created a structure, she was not required on-site like an SCV; rather, she built in much the same way that a probe creates protoss structures.
The queen had base defense duties, including laying eggs that hatched into suicide attackers.