Help understand the difference between Exact and Wildcard/regex blocking

Hello,

Can someone please provide examples that show the difference in blocking using exact and wildcard/regex?

Case1:

I understand what the Exact does. If I add “adservice.google.com” as EXACT then it will only block “adservice.google.com”.

But what if I want to block anything that has the domain “adservice.google.com” in it?
for example, xyz.adservice.google.com or “ANTHING”.adservice.google.com?

I have been doing this by typing “adservice.google.com” in the search bar on the pihole blacklist page and then I click on wildcard or regex but I am not sure if this way is even correct.

Case 2:

What if I want to block anything that has “adservice.google.com” in it? in other words, “adservice.google.com” could be at the beginning, or in the middle or at the end of the domain that I am trying to block?

Case 3:

What if I want to block a domain that has a specific word but that word could be at the beginning of the domain or middle or at the end?

For example, I wand to block the word “hsd1” but the domains that could have this word might have it at the beginning, middle or end

xyz.hsd1.com
or xyz.com.hsd1
or hsd1.xyz.net

Thanks