Deactivation And Deletion Are Very Different
- Deactivation hides your account. Your data is preserved in case you wish to return.
- Deletion destroys your Facebook data. You cannot recover it.
You can always backup your data and then delete your account.
Here is Facebook's summary of the differences.
A deactivated account allows Facebook to keep your data. It is still valuable to advertisers and other third parties.
As a result, Facebook encourages account deactivation as opposed to full deletion of your data.
If your intention is to permanently delete your account, do not be fooled into deactivation instead.