'Steakburger', in some circles, is interpreted as a hamburger with delusions of grandeur. That's actually not the case - a steakburger is a hamburger made with steak - leaner, poncier meat, as opposed to the mangled cow bits that compose 'hamburger'. It's like comparing whiskey and bourbon.
Lest that sound perjorative, think again. I really like my bourbon...
A burger made from steak is much more dense - meatier - but also less flavorful.The taste difference actually comes from the quality of the meat. Just as the full taste of a sirloin comes from the marbling, the taste of a burger comes from the fat. And you simply get more if it with the cheap stuff.
So, while a steakburger is still a good burger, it's not a hamburger.
It's worth keeping this in mind at the supermarket - despite being three times the price, that '99% Lean Ground Steak' really won't make the best burgers. (Incidentally, it's still worth shelling out extra for free range and organic... just because you want to keep the fat doesn't mean you need to keep the extra chemicals).