Delta Restore

[admin]

Yes, both restore only the changed blocks on the disk, where they differ may be in the way they look for changed blocks on disk.

Macrium Reflect can either look for changed blocks at restore time, or keep track of then as it goes.  The latter speeds up time to do a restore, but it does use a slight bit of resources keeping track of changed blocks.

Yes, you're right that the Changed Block Tracking (CBT) technique takes up some resources because it tracks storage blocks that change over time, just because computers nowadays are fast enough that we don't feel its effects.