Do Transactions Need Operations rather than Data API

I was following your advice here about using Transactions to reduce API calls to improve performance and reduce costs. I also watched your video about how Transactions can improve data integrity with an all or nothing approach to completing the operations.

To the question at-hand though, do I need to change all of my Data API blocks to Operations inside a Transaction if I want it to work as intended and count as one API call? Or is merely moving a Data API into a Transaction sufficient? I’m not sure what the difference is between a Data API block and an Operation that does the same thing.