Cartridge dimensions are the same. It’s the chamber dimensions that vary.
That’s why .223 Wylde is such a good chambering. Sure it is a compromise, but accuracy is better with .223 Rem than with a 5.56 chambering.
per Hornady… “The 5.56 NATO chamber has a .125” longer throat. This allows approximately one more grain of powder to be loaded into a 5.56 NATO cartridge; this is what gives it higher performance than its 223 Remington cousin.”
https://www.hornadyle.com/resources/le-faq/what-is-the-difference-between-556-nato-and-223-rem-ammunition