FL Studio is the core program, the most advanced version is FL Studio Producer Edition.
XXL (obsolete) and Signature Bundle are 'bundles' or a package of FL Studio Producer Edition PLUS extra plugins at a discounted price. They are a great way to buy FL Studio and plugins as you save $100's compared to the individual sale prices.
It is possible to upgrade from XXL Bundle to Signature Bundle in our web shop (when you have XXL active).
The upgrade will add the plugins Maximus and Hardcore to your FL Studio.
To see all the features included with each Edition and Bundle see our edition comparison page. In summary:
How to know you have the correct version registered?
The registered FL Studio program may say at start-up that you are registered for Producer Edition. However, when you check the menu help > about window inside FL Studio, you will see Signature Bundle / XXL bundle is listed as active edition.
Please check this knowledge base article:
How to know you have the correct FL Studio version registered?