Marketplace title difference wp7 and wp8

Question

I try to create wp7 and wp8 versions of my app, but I'm confused about Marketplace (Windows Store) title.

For WP7:
I use Windows 7 + VS2010 + WP7.1 SDK, and what I have:
When I open Marketplace Test Kit I need to add Marketplace title 200*200 pixels.
I also found this article: Creating Windows Phone 7 Application and Marketplace Icons, where Marketplace title also 200*200 pixels.

For WP8:
I use Windows 8 + VS2012 + WP8 SDK, and what I have:
When I open Windows Store Test Kit I need to add Windows Phone Store app image 300*300 pixels.
I also found this article: App submission requirements for Windows Phone, where Windows Phone Store app image also 300*300 pixels.

My question is:
Why it's happens?
Why I need to add same image with different size for each version of my app?

Answer 1

Windows Phone 8 introduced higher resolution screens (768x1280 and 720x1280). This is up to 1.6x pixel count of WP7.

So to make sure the images look good on the higher resolution phones, a higher resolution image is required for your icons.