Ok so when we talk about snapshots in VMware deleting means merging the snapshots to the base disks. for Example if you have base disk of 5gb and child disks of 2gb ( child disk is nothing but your delta.vmdk which is responsible for keeping the track of changes also known as child disk.) So lets say u deleted the child disk the content of the child disk gets merged to the base disk and your snapshot manager shows no snapshots at all.
Consolidating is a way to make sure if there are no snapshots in your snapshots manager then their should be no delta in the datastores so consolidation is the way by the help of which we are making sure that all the delta gets merged to the base disks so as you do not ran out of space in your datastore.
Kindly mark this as helpful/correct if this answer your query.
Rgds
Kanishk