The basic difference between Backup & disaster recovery solution is RTO & RPO.
Backup: In backup, the backup frequency defines the RPO & time to restore data defines the RTO.
disaster solution: in disaster solutions most of the organization will keep the real time data movement from source to Target so RPO is near zero & the RTO is just a network changing from source to Target. So there is small period of downtime of the production/
Backup is to have multiple copies with longer period.
Disaster recovery will give you business continuity without down time.