Different Prices?

I am frequently on the microsoft store and while I may be late to the game, I decided I wanted to download Destiny 2. I click on the Destiny 2 icon and it says “not sold seperately”. Okay? Why would it be sold in a bundle? I check on my phone and it says
Destiny 2 : Legendary Collection (Includes the game) for $19.99, knocked down from $59.99. I go on my Xbox One to purchase it and it is $59.99. I try restarting my xbox and it still says that? Why does it do that and can someone help? It is my first time on
the forums so I don’t really know how to navigate it. Thanks for reading this.

:)