When you take a VM snapshot, the virtual disk file (VMDK) is set as read-only and a delta file is created - writes are then made only to the delta file.
So yes, much smaller than a clone as that would be a full copy of the VMDK file.
However, if you look through this forum area, the Workstation area, or the vSphere area you will see many who have problems with VM snapshots.
Why? From the moment you took the snapshot you were dependent on 2 files working perfectly in order for your virtual disk to be intact and functional - and the more snapshots you have the more files you are dependent on.
One other thing to understand, over time your delta VMDK file is going to grow, depending on the blocks of the virtual disk written to by the guest OS - running short on host disk space leaves users coming here often.
I would never want to leave a snapshot on a VM for any length of time - to experienced VM users they are a short-term thing, used during backup processes, and OS and application patching or upgrades.
If your use case is short term, it can be a useful function - but be warned...
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