Sometimes MS SQL Replication developers use similar names for similar meaning but which can have very different results. These settings both specify alternate location for the Snapshot files, however, one is set at the publication and one at an individual subscriber.
The alt_snapshot_folder parameter is set at the Publisher for ALL subscribers. This can be set at publication creation or after the publication is generated. When this option is set, a new Snapshot is generated and copied to the alternate Snapshot folder.
@publication = 'TranUpdate',
@property = 'alt_snapshot_folder',
@value = 'D:\temp\CHRISSK1$SQL2K8_ADVENTUREWORKSLT_TRANUPDATE',
@force_invalidate_snapshot = 1
The AltSnapshotFolder setting is made at an individual subscriber level and does not require a reinit. All it requires is you first copy the current Snapshot files to new directory. This works great when you’re encounter problems delivering Snapshot over WAN. Simply ZIP and copy snapshot to drive on local subscriber the set the Replication Agent’s AltSnapshotFolder property pointing to that folder. Agent now applies snapshot using local copy and not copy across the network.