i was a D2 kicker..and d1 level soccer player...
Go kick me 25 field goals and kickoffs then go hit some crosses at soccer..then go back and kick footballs...its mechanically very different. in my case i would hit the footballs very fat.
you're right a lot of it's very similar--thats why soccer players sometimes transition nicely..but there are also major differences
the most obvious difference would be the follow-through.....in football---you want your leg to follow the ball--through the uprights--your plant leg would be the first thing that lands---you should swing with enough force to bump your body forward..
----in soccer the foot you land on after a shot--should be the foot that you took the shot with..
in football you look down at all times, coaches ream you for not keeping your head DOWN...in soccer once you graduate to a decent league coaches teach you to keep your head up--you should know where the ball is at all times..nothing more than a glance is needed
two-three steps backwards and one over is largely a a timing mechanism.....I could hit a 45 yard FG with 1 back 1 over--it does shorten your time and allows you to get off a kick with less pressure--BUT it also gives you less time to adapt to error in the snap/hold/etc.