See, when you hold the World Heavyweight Championship there is an illusion there that the title is not just a company title, but instead a title that spans the entire world which includes hundreds of wrestling companies and promotions. Simply put, they don't call the title the “WWE World Heavyweight Championship”.
Actually, this is exactly what WWE implies with the name of the belt. I don't think it makes it higher than the WWE title, but it is the illusion WWE tries to create. When WCW had dual titles from '93-'94, the big gold belt (today's WHC) represented the NWA title belt, which did represent promotions all around the world, and then there was the WCW title for the company. When NWA pulled out, WCW renamed the big gold belt the "WCW international world title," representing "WCW int'l," a fictional international subsidiary, so as to imply that it still represented promotions outside of WCW. Hence, stars from New Japan Pro Wrestling held it (though maybe when it was still called the NWA title, but to a WCW viewer this was the same title). So when the WWE uses the big gold belt to represent the WHC, and claims it represents George Hackenschmidt's (sp?) 1905 world title, they are completely implying that it represents much more than WWE. That's why they describe the world title as "coming to WWE in 2002" (even though other times they say it officially started in 2002).
The WWE title is just better, in kayfabe and reality. I like to convince myself they're equal, but its just the truth. If John Cena and the Undertaker fight for it, it'll be better, and it was definitely close to or equal to the WWE title when Edge/Undertaker/Batista were fighting for it. But, as much as I love Del Rio, Sheamus, and Big Show, they're not Punk/Cena/Rock.