Have you looked into help file yet:

Hi Ravi,

If you are looking for some real time scenario usages for the scope of the data pages then you can look into this explanation. Hope this might clarify your doubts.

Regards,

Mahesh M

Below following pdn link may also give your the help:

https://community1.pega.com/community/pega-academy/question/data-pages

Hi

Node Level: 

If we specify a page in node level, then it can be accessed by all the requestors in the particular node.
Requestor Level:

If we specify a page in Requester level, then it can be accessed by all the threads opened by the requestor.
Thread Level:

If we specify a page in Thread level, then it can be accessed only by that particular thread.

Hi Ravi,

Please check the below.

• Node – any requestor executing on the current node can access the pages.
• Thread – the page is created in a single requestor thread, and can be accessed as often as needed by processing in that thread. Access by separate requestors causes the rule to create distinct pages, which might have different contents.
• Requestor – all threads for the current requestor.

Thanks