New
#11
If you're using Windows 8/8.1, anything in the Store is available to you to install and use.
If you're using Windows 10, there are two versions of the Store: the regular Store (which I believe is the same as the Store in Windows 8/8.1) and the beta store [Store (Beta)].
The Store (Beta) cannot be seen nor used in Windows 8/8.1. It's a Beta and will eventually replace the old Store.
It's my guess that Windows 8/8.1 will continue to see only those apps in the Store that are compatible with that OS while Windows 10 will see all the apps that it can run.
As far as I know, you cannot download anything from the Store; you have to install it if you want it. Which isn't normally something I want to do.