Can you go into a little more detail on the differences?
I can only speak to what I observed based upon my experiences flying Marine then Army aircraft, so this may not be what others may or may not have experienced.
First, I found that the NATOPS basically told you the few things you could not do, and as long as you flew following the listed procedures and limitations you could almost anything you wished. The TM, overlaid with the ATM (Aircrew Training Manual) told you what you could do, and you never did anything else.
For example, for a full year we were prohibited from doing touch and goes with the C-12. Why? Because the ATM had no procedure for a T&G. There was a procedure for landing, and a procedure for taking off, but not one for combining them. It took Mother Rucker a year to determine a T&G was safe, as attested to by every student pilot IN THE WORLD was doing them.
Tactically, the Army was riveted in the procedures used during Vietnam. Flying dash-4 of a four ship flight in the AH-1F, I saw I was getting a little sucked with 3. At a check point I decreased my radius of turn to close in on 3. The IP I was flying at started screaming on the IC about how the other aircraft had cleared the route and by my slight cutting of the corner I was putting us at risk. At the debrief I discovered that, at least in this Company, they had no concept of combat spread and flew straight lines behind each other, stating “We did this in Vietnam.”
On my first pref-light of the Cobra, the IP asked me one of those mundane/expected flight school questions, “what is the path of air as it goes though the engine?” The flight school regurgitation had nothing to do with combat survivability. I of course answered the blaw blaw blaw. But then explained that was not the important learning element, which was “How many engines do you have?” With only one, If it fails, you land, period, no options.
And formation flying in the Army was as “same way-same-day” as it can get. Coming from Naval Aviation where tight precise formation is part of your lifeblood, this was a whole new world.
In the Army, aircraft are just another combat arm, or more precisely, just another rifle. There was little discussion of the combined arms concept, just go that way and do today's mission. In addition to the whole WOPA thinking anyone Commissioned is less than whale shit and is to be discounted immediately.
Also, Army Aviation is very regimented in-duties as an aviator. The Maintenance Check Pilot, IP. SIP, Instrument Instructor, etc. are all distinct duties that never cross. Where in Naval Aviation you might hold several of those duties at the same time. At one time I was a HAC, DOSS, Maint Chk Pilot, SAR Chk Pilot, and a few other things at the same time. This is unheard of in the Army.
These are but a few of many examples that make it interesting at least, should one change services as an aviator. I am not saying one is better than the other, just that the mentalities are different. And I personally prefer the Naval Aviation approach.
Again, this is based on my experiences and may not be what others have experienced.