Are Plays within playbook also lists?

Going through the session - https://kodekloud.com/topic/ansible-playbooks/ one of the point that was covered was tasks are lists within a play and their order cannot be swapped however properties within dictionary can.
I suppose even the plays are also lists within a playbook and hence even they cannot be swapped. Is my understanding correct?

The default behavior of Ansible is to run each task in a playbook simultaneously on each host mentioned in the group of hosts.

When you execute a playbook, in each play, all roles will be executed first, followed by the tasks, top-down in the order that they are written.