It is necessary to understand that in these two – the initial thought, which is Ein Sof, blessed be He, and also the imagined design of the details for execution at the right time – there is not yet there even so much as a trace of created beings, since everything is still in potential, not realized in actuality. It is the same for people: Even if one calculates all the details, from the wood and the bricks to the metal – including what must be done at the time of the execution – it is as yet only a free-floating mental substance, without even a trace of any actual wood or bricks.
The only difference is that in the case of people, the imagined design is not considered actual reality, whereas in the Divine thought it is actual reality, inestimably more so than the actual, real created beings themselves.