No.. interally, they're both the same without upgrades.
You'll notice how higher-end guns don't shoot 400fps stock. There's a reason for that. Companies that make low-end guns know n00bs jump all over FPS.. so they'll make a gun and stick in a really powerful spring the gun was never designed to take and advertise "400+ FPS".
Armalites use a Version 2 mechbox (SR-25 uses a modified V2). The version 2 mechbox has some weakpoints, and without certain upgrades or a reinforced shell, repeatedly shooting at 400FPS will break it.
"Someone in a Prius tried to race me at a stop sign the other day. I couldn't believe it. I had him for the first 100 feet or so but I can only walk so fast."