What's the difference between services.etcd.snapshot and services.etcd.backup_config?

#1

rancher2.x etcd backup and internal rke’s etcd snapshot, what’re their differences?

services: 
  etcd: 
    backup_config: 
      enabled: true
      interval_hours: 12
      retention: 6
    creation: "12h"

    retention: "72h"
    snapshot: false