Objects in mirror may be closer...
Westwood has done an amazing job at scaling everything in the C&C universe properly. Since you're now "within" the game, so to speak, Westwood has had to think about and implement exactly what the interior of a Hand of Nod would look like. What about a tiberium refinery? Renegade allows you to run around massive outdoor environments and also enter buildings and explore sizeable interior structures, many of which have multiple rooms and floors. Enter a refinery and you'll see tiberium running by on conveyor belts as it is transported to processing. You'll also see a parking space for the Harvester that goes with that refinery, as well as personnel manning the refinery. Expect the same type of detail with every building you run into.
Better break out a bigger gun
So you're a commando with the ability to drive big tanks and carry around rocket launchers. Why not level a building from outside with your firepower? Why bother going inside? The answer is that it takes a lot longer to destroy a structure by shooting at it, and you don't always have the luxury of driving a Mammoth Tank around. It's easier to use your C4 to take out a building, but you can't just slap a brick of plastique on an outer wall and expect to bring down the house. To do so you'll need to infiltrate it, find the building's master control terminal, and plant there.
Renegade's graphics are clean and polished - while the in-house engine probably won't give id or Epic a run for their money in terms of technical details or sheer beauty, it does what it needs to do and runs pretty fast. The vehicles each have their own feel due to torque, power, inertia, and mass. The engine also allows for smooth, instantaneous transitions from indoor to outdoor environments. Textures are crisp and detailed, and the character models exhibit excellent animation. You'll also see environmental effects, like weather, and advanced lighting and shadows that cast over the models.
Westwood has even incorporated location based damage in the game. Head shots do more damage than body shots, which do more damage than shots to the extremities, etc. Shots to different areas will result in different reactive animations. In terms of sophistication, it's well beyond Unreal Tournament's system, and probably a bit better than Counter-Strike, but not quite at the level of Soldier of Fortune.