I get that it's different, but not that it's "totally" different. In fact, I would think that if somebody could do seated militaries with 225 that they've already shown the shoulder strength to press 2 wheels in a standing press. Plus, you can push-press it a little with your legs.
Now, for me, I almost always fubar my lower back doing standing press because of my APT and lack of shoulder mobility directly overhead, but if your shoulder mobility is good and you've got the muscle. It should be straightforward.
Well if you start to push press it then you are doing just that - a push press. That is another separate exercise. I can push press 30-40% more than I can strict press and some lifters find the gap between the two is even greater.
The seated shoulder press is closer to an incline bench press than the standing strict press.
Pressing 225 overhead in the seated position is a very impressive display of strength but I would not imagine that many people who can do it would find that they can automatically do 225 in the standing strict press.
One of the best things a lifter can do who has been benching, seated pressing etc. is to try some standing strict presses performed correctly (no leg drive, bar starting from below the clavicles at the beginning of each rep and finishing with the arms fully locked out, traps shrugged upwards and head under the bar). It is usually extremely humbling but can tell you a lot about what you need to strengthen as a lifter which in turn can further increase your bench and other such lifts.
