Backup types (full, incremental and differential) define which data each backup run copies. A full backup copies everything; an incremental backup copies only what changed since the last backup; and a differential backup copies everything that changed since the last full one. Incrementals use less storage, but a restore needs the full backup plus every incremental, while a differential restore needs only two sets.
Go deeper on the TecnetBlog: Real-Time Backup vs. Scheduled Backup
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