"Carbide" sizing dies are steel dies, They have a ring of carbide "glued" in, and work well without lubrication for straight cases, and short cases with minimal taper. Longer cases with more taper require lubrication. Rifle cases require lubrication and carbide dies for them are rare and extremely expensive. (don't know today's prices, but decades ago, when a carbide pistol sizer die SET was $30 a single carbide sizer die for .308 Win was $150)
If you lube straight wall pistol cases, a carbide die works even slicker.
also be aware that if the press ram (shellholder) contacts the carbide ring the carbide can crack, requiring replacement of the die.