The difference between Deluxe vs Standard is that Deluxe includes the Deluxe Edition Bonus Items, which I believe are
- West Weald Tharriker Mount
- Skingrad Guard Mastiff Pet
- Skingrad Vedette Armor Pack
- Ulfsilds Tome of Legends Memento
- Colovian Emote Pack

Note that there are two versions of the Deluxe edition:
- Deluxe Collection
- Deluxe Upgrade

Both include the Deluxe Edition Bonus Items, but Deluxe Collection also includes the previous chapters and their bonus items, whereas Deluxe Upgrade is just the new chapter for those who already have or who don't want the previous chapters.

The differences are spelled out here:

https://www.elderscrollsonline.com/en-us/joinus/

Edit: Also, IIRC, yes, you won't get the extras until the chapter goes live in June. Note that the Deluxe extras are separate from the pre-order extras-- if the pre-order extras are still available, since there is a cutoff date for those to incentivize people to pre-order early.

Edit #2: Okay, the scrolls you referred to are pre-purchase bonus items which will become available when the chapter goes live:

https://www.elderscrollsonline.com/en-us/news/post/66073

I don't see a cutoff date mentioned, so I guess maybe the pre-purchase cutoff is when the chapter goes live, and the cutoff date that I had in mind was for the additional early pre-purchase item-- the Welkyndstone Ruins Pup non-combat pet-- which is no longer available since that early pre-purchase cutoff date has already passed.