The die dimensions should be identical.
Case capacities will be very close.
The bullets are the same, except that you can probably use heavier bullets in a 556 rifle.
Many of the powders would be identical.
In other words, they are virtually identical.
You'll find a lot more published data labeled for 223 than 556.
Still happily answering to the call-sign Peetza.
The problem, as you so eloquently put it, is choice.
He is no fool who gives what he can not keep to gain what he can not lose.
-Jim Eliott, paraphrasing Philip Henry.