BudsGunShop.com - Caliber

Yes, you can shoot both.
The exterior (physical) dimensions of .223 and 5.56 ammunition are effectively identical.
5.56 ammunition may be loaded to higher pressures than .223 ammunition.
5.56mm chambers are dimensionally larger in certain critical areas than .223 chambers.
Given the same ammunition, 5.56 chambers will have lower pressures than .223 chambers. Information video here : luckygunner.com/labs/5-56-vs-223/

Artak, the 5.56 has higher pressure, any AR that's 5.56 will shoot .223, but it's not a good idea to 5.56 though a .223