Yes, they are RC and they are a great replacement for 1:18 tanks if you don't mind getting your hands dirty on occasion.
They come out of the box with 1:18 detail and they even play lasertag with each other if you get the IR versions.
The 1:16 RC tanks can be just about anything you want them to be... static model, diorama centerpiece, or a down and dirty tank that actually climbs over stuff with real metal tracks, firing guns, authentic sounds, and much more. As you noted, the detail is as good or better than 1:18 right out of the box, and the possibilities for improvements and upgrades are limited only by your imagination, modelling skills, and wallet.

One guy over at RCU has developed a functional tank commander figure that sits in the turret hatch, and whose body parts move on command using tiny servos and gears, and it's just one example of the resourcefulness and creativity of the 1:16 guys, there's almost nothing they can't do, or won't at least attempt. I found a couple more pics of the new HL Panther G that a guy in Germany did, and while Oz's tank looks great, this is more like what I had in mind for mine when I get around to painting it....

Gen. George S. Patton Jr., 28th Regimental Colonel, 3rd Armored Cavalry Regiment, U.S. Army, "Blood and Steel"