Push Notifications

Frappe HR
,
16

I Notice the following Apps, and i am confused

tridz-dev/frappe_notifier

tridz-dev/erpnext_fcm: Firebase Cloud Messaging integration for sending notification created in ERPNext/Frappe to users as push notification.

and also,

All these Apps confuse me, and t=do they relate to the Push notification System, i need some clarity kindly.