People often use the terms "push notification" and "pop notification" interchangeably, but both refer to the same concept. Both terms describe a message that a server "pushes" or makes "pop up" on a user's device. These notifications can appear even when the user is not actively using the app, making them a powerful tool for user engagement and communication. There's no technical difference between the two terms, and the choice of terminology often depends on the context or personal preference.