What is the differences between purchasing a list from listsource or using a software like myreipro to pinpoint possible sellers?

@Marlon Jackson they all get the data from the same sources. 
Listsource  is a one time purchase of a list of property owner names and addresses only. You then need to take that list and get the phone numbers and email addresses.

Services like myreipeo and others are subscription based and will include the appended information. They also update the list info regularly instead of you buying a new list every month then skip tracing (appending the data) so it’s basically an aggregated service.