What is the difference between sending push notifications to all users, specific users, specific user groups, and in a specific geographical location?

All Users:

Under All Users tab, app owners/moderators can send push notifications to all app users.

Specific Users:

Through Specific User push notifications section, app owners/moderators can send push notifications to specific users.

User Group:

In User group push notifications, app owners are allowed to send push notifications to specific User Groups.

Specific Geography:

Geographic push notifications provide you facility through which you (app owner) can send push notifications to app users in a specific geographical area instantly or on a scheduled time.

Setup Geo-Fencing:

Geo-Fencing push notifications allows you to preselect the area and provide default push notification message, which will be delivered once any app user enters the Geo-fenced area.