What is pre-installed expansion pack?

[Sukanta]

Dear Experts,
There are few pre-installed expansion packs in Yamaha website. If I install these packs, what will happen with my existing factory styles?I've sx900. 

and How to install premium packs in sx900 from Yamaha website? There is no option to download for sx900.

[EileenL]

Installing Yamaha packs will not alter any on board styles or anything else.
If you are referring to the packs that are installed in the memory when  you get the keyboard these will be deleted if you add new packs. You can download these packs from the download site and import into your YEM so that you can always load them in again along with any other packs you may chose as long as you have room for them on the 1Gb of memory in the keyboard.

[Sukanta]

But, why these are shown as pre-installed? What is the difference with other normal pack?
I've attached a screenshot.

[attachment deleted by admin]

[DerekA]

It was a bit of a marketing ploy, to provide some packs free with these models and for convenience for them to already be installed at the factory. Other than that, they are not different in any way from the other Yamaha packs.

Since then Yamaha decided to make all their packs free anyway.

[EileenL]

The difference is that you can not add other packs to the Pre installed ones. That is why I told you do download these packs from Yamaha so they then can be loaded into the YEM and used with other packs.

[LaHawk]

The 4 Pre installed packs from the factory are kind of like "samples" . If you add other packs via YEM, these 4 "samples" will be hidden. However you can roll back to the 4 original "sample" packs (and those 4 only) on the keyboard, because they are not actually deleted.

You can also choose to add any or all of these 4 original sample packs along with any new packs in YEM.

The pre installed packs for SX-900 and SX-700: https://uk.yamaha.com/en/products/musical_instruments/keyboards/arranger_workstations/psr-sx900/vse.html#product-tabs

Additional Expansion Packs: https://uk.yamaha.com/en/products/contents/keyboards/vse/index.html