The new *star services function in the same way as the original reverse NS and MX to provide you with all domains sharing the same nameservers or MX records.
However, you will find that this search gives you much more diverse results.
For example, domain.com has ns-1250.awsdns-28.org as one of its NS records. A simple Reverse NS lookup shows that this NS has 2,588 connections /to date/. However, if you run the new NS*, you will come up with 20,637 related domains by NS, ie all nameservers under the domain awsdns-28.org. The same applies for the new MX*, only the number of connections is different.
This can be particularly useful if you need to find more interrelations between domains and also, to uncover some domains that otherwise may be difficult to reach.