I think the most common confusion would be the "mythical, knock down power" and energy! Energy is important, but shock, organ damage and blood loss is what kills! Nothing "knocks them down."
With the same cartridge, bullet, and shot placement, some fall, and others run. I've seen deer stand there and act as if they didn't get hit, and then keel over dead, others that run straight forward, are not "knocked off stride!"
In the world of velocity, the bullet has long since passed through them before they even think about running!