If we enable sensitive data redaction in the Heap UI, is this data transferred to the Heap Cloud securely?

I am trying to understand the best way to implement sensitive data redaction. As far as I could see, there are two options to do so: indicate data to be redacted either in application source code or in the Heap UI. What is the difference between these 2 options? Am I right that if we choose to indicate this data in source code, we prevent sending data in non-masked form to the Heap Cloud at all? And if we choose the setting in the Heap UI, am I right that the data before reaching the Heap Cloud is sent from our apps in non-masked form?