The standing position for those extra Takbirs has passed. Saying them in Ruku is therefore called Qada because their prescribed place has changed.
Yet Ruku resembles standing: part of the body remains upright, and Ruku stands in the place of standing in this explanation. The Takbirs therefore also resemble performance in their place. This is Qada resembling Ada.
The extra Takbirs have no separate equivalent as worship outside prayer. Notice that the resemblance here concerns place and posture, not simply whether the date is earlier or later.
- Why Those Takbirs Resemble Ada