Supposing you arein multisite (at Sites -> All Sites) and you click the Export button in your subsite blog ID: 3 – you might see this Export type setting:
The difference between the two
Basically, “Export as subsite backup” is a short cut of “Export to multisite format” when you are creating a backup of the same multisite subsite. For example – when you click Export button of sub-site blog ID: 3 and you want to create a subsite backup (like the above screenshot).
When you select “Export as subsite backup” – it will create a Prime Mover WPRIME package targeting blog ID: 3 (a backup of blog ID: 3) which you can restore to a subsite with blog ID 3.
However if you select “Export to multisite format” – an additional text box will slide down asking you to enter the target blog ID:
Now if you enter 3 in the text box (as blog ID) – The resulting package between “Export to multisite format” will be same as “Export as subsite backup”.
In other words – “Export as subsite backup” – is the same as “Export to multisite format” with the blog ID of the current site you are exporting. This feature is added so user won’t be adding the blog ID number manually every time they want to create backup. It saves time and convenient as you don’t need to enter the blog ID every time you create a backup.
If you enter a different blog ID in the “Export to multisite format” – the package is now targeted to a different subsite – it’s no longer considered as a subsite backup package since it cannot be restored to the current sub-site (the blog ID is now different). This is usually used when you want to migrate subsite to a different subsite with diferent blog ID. For example – if you enter blog ID: 10. It will create a multisite package targeting to blog ID 10.
Please read this guide on the explanation of different Prime Mover packages and how it can be applied to different migration/backup scenarios.
If you have follow-up questions on this topic – please ask it via our official contact page.