I did both.
What I experienced in the army was the product of the times I was in the early 2010s. It was the surge in Afghanistan. Can't hover the helicopter? Can't pass the PT test? Don't know your EPs? Here are some wings... you are now your unit's problem. The only thing that would get you kicked out was a DUI. Going through as a young 24-year-old WO1, it did not try at all. Drinked and partied all the damn time and still got my top choice of CH47s.
I thought UPT was way harder than Rucker. But when I went through I was way more mature. I got hired off the street by a tanker ANG unit and had to go through the full UPT. I was the last one to solo in my T6 class, even though I was a 1500-hour combat aviator in a helo. I guess I was just used to taking it slow in a helo. I would joke around telling folks at Vance that I used to do my ILSs at 60 knots... why? because I could. Now, going from Vance to OKC on a Rwy 17-day was a fast and rude awakening.
I don't think it's a good metric to compare the two. The army sucks the fun out of everything and will try their hardest to change what should be a good experience into something horrible that will make you want to retire. At UPT, I lived for drop nights and the weekends. Party hard with the bros during those but come Sunday night it's time to hit the books and chair fly.
But for your original question, I have the following:
ARMY Rucker:
Easy
- The school program. Memorize a few things here and there. Doesn't matter if you even know what you're talking about, as long as you can spit it out verbatim, you will pass with flying colors.. - Flying VFR. Because flying instruments is very hard for all Apache pilots and MTPs.
- The standard and the ability to make it. I had people I graduated with who had no business being aviators. But the Army needed the numbers, so here are some wings. I remember day one at Rucker we had the brigade commander tell us that the flight school policy was "No Flight School Student Left Behind"
-I think the flying part is probably way easier nowadays. You fly UH72s in primary (no more TH-67s or OH-58s). The 72 has a pretty advanced flight control system that has studs being able to hover after perhaps an hour or two.
Hard
-The Army. You will graduate and think you are god's gift to aviation. You are not, and here are some field training exercises and ground training shit to prove it and to make you feel like an infantry guy. Also, here is a two-piece flight suit, a PT belt, and Eye Pro... all of those are inspectable items by the sergeant major at any time, so best be ready.
-Being a warrant officer - Oh you think your job is a flying-only track? what a scam... and to prove it, here is some paperwork on stands, safety, and ops that an officer should be doing, but it's easier for the army to make a warrant do it for half the price.
-Being a commission officer - oh you want to fly? here are some awards to type and some inventories that need to get done. Nobody will be your mentor and warrants will see you as more of a hazard to the flight since you probably know the ops limits of your computer better than any real helicopter anyway.
USAF UPT:
Easy
-Wearing a one-piece flight suit and finally feeling like a real pilot.
-Pulling Gs. Because doing a 60-degree bank in a helicopter is a pretty serious maneuver.
Hard
-The information overload and the fast pace of things. I remember coming back from a flight at Vance early during T6s. I was tired and beat up from all the U's my FAIP just gave me. I saw a random IP walking straight toward me to ask me what I was doing as soon as sat down in the flight room. Studying I said... Only to hear him say "No your not. We are stepping into another jet so let's GO! You can brief me on what all you need to clean up as we walk to the jet."
All finish up by saying that the lifestyle in the USAF is a million times better than the Army. If your post originated as a product of frustration because you're having issues being selected to AD, ANG, or reserves, my advice is to KEEP trying dude. Don't look at going Army simply because the USAF is being too selective. It's supposed to be selective! The army should only be an alternative if age is not on your side.
Hope that helps.
Cheers