So “Delete a thing” would be used if you have, for example, a Delete button in your repeating group on each row. So you know exactly what thing you want to delete. “Current cell’s Service” or whatever it is.
“Delete a list of things” might be if you wanted to delete ALL the Services. Or if you had check boxes in each Repeating Group cell, so the fairly common “tick the boxes and then Delete Selected” way of working with lists. In that case you want to delete all the things in a list of things. This “list” could be the result of a Search (so “All the Services for this User”) or something you have created by adding ticked Services.
“Make Changes” is much the same. If you know the “thing” you want to change then you can just update it - so for example maybe you are changing the cost of a service in a particular cell.
“Make Changes to a List” makes the SAME change to a list. And this is often a source of confusion in Bubble, firstly you tell Bubble the list (so perhaps the result of a Search) and then you tell it what change you want made to EACH thing in that list.
An example of the make change to a Single thing. I have one Question on my page, I want to change just that.
And example of make changes to a list. I have a list of users on my page that I have Displayed in a Repeating Group. I want to Add something to EACH User in the list.