Let’s start a mental experiment, starting with the earth as it can be seen from space, with time come to a halt. For the purpose of experimentation, that is the initial design of interest.
Next let’s imagine having an instrument to observe. What can be seen through the eyepiece determines the whole, at the start the whole earth. What can be subjectively considered the significant structure of the whole, is the architecture.
When zooming down, the “whole” boundary changes. What can be subjectively considered the significant structure relative to the newly determined whole, the architecture, changes too.
The instrument provides an infinite zoom capability. Zooming down can continue, down to continents, countries, cities, buildings, ultimately to the atomic level and even beyond. All in all, the overall design i.e. the whole of the earth down to its tiniest part wholes does not change at all. Architecture is thus the sum and the part because as one zooms in and out ultimately everything is covered, all design.
Architecture is design, design is architecture.