How to display specific blocks for specific roles alone w.r.t domains and subdomains
Hope this will help you,

In Drupal 7 you can use these modules


Domain Context - It allows administrators to set specific settings for each of their domains that are using the same code base.
Domain Blocks - Enables domain specific visibility settings for blocks.
And for specific roles for each block you can select the roles. Go to your specific BLOCK configuration and select the ROLE in BLOCK VISIBILITY SETTINGS