I'm going off memory here, which isn't what it used to be.
I think the Win is lightly larger than the Norma at the base of the body, some thing like .501, .502 for Win and .500 for the Norma. So it is conceivable to get a tight chambered Norma that may have difficulty chambering Win brass. But the Norma brass will chamber in either and just fireform to your chamber.
I have the 6.5-284 Win and have no problem using Lapua brass, as a matter of fact I"m rather fond of the stuff.