Chris Roberts, who created the well-known Wing Commander series in 1990, managed to raise millions of dollars on Kickstarter last fall for his upcoming Star Citizen, eventually collecting so much money from individual backers that he could return the budget he'd taken from "formal" investment firms. "Even nice investors, they want a return at some point. They have a slightly diff agenda than I do," Roberts told Slashdot. "My agenda is to build the coolest game possible."
Herein lies the difference. Kickstarter backers are not seen as actual investors in the project by the project owners, but rather as a way to informally fund games that the developers want to work on without feeling like there is any real obligation to those who funded it. To paraphrase what Chris Roberts stated, he couldn't care less if it ever makes any money as long as he gets to build the "coolest game possible". Without the incentive/pressure of investors looking for a return however, there will always be "just one or two more things" to finish up and the game will never actually get released.