You probably are, as I've done multiple hikes in the hundreds of miles distance (one of which was even out there in the Rockies). If you were a more experienced hiker than I am I doubt you'd have mentioned that possibility.

I've yet to do Rainier, but if it's actually got any grade or technicality it'll be the first for me out of hundreds of miles worth of trail out there. Being high elevation doesn't make a hike difficult, and switchbacks are boring AF. They're the treadmills of hiking.

Meanwhile, yes the Green and White Mountains have been tougher than anything I've found out west yet. Going straight up rocky terrain instead of winding around on a horse graded trail is a huge difference.