On top of the fast track without normal human trials & testing, it's not your typical flu shot. Different in that these crafted juices program immune system responses to targeted virus. Whereas vaccines I'm used to receiving are concocted with dead or weakened virus, which prompt a natural immune system response, prepping the immune system to wage war should the targeted virus later infect my body.
Of course, I'm an engineer, so I could always be corrected by an expert immunologist, molecular biologist. But this is what some experts say, and how some describe the differences.