The main materials of the case and frame are different for the Raider and Titan. The Titan has a metal case, while the Raider has a plastic one. This is clearly visible in the photos of the disassembled laptop
The new Raider 18 drops many of the "unnecessary" features of the Titan 18 while keeping the same high-end CPU, GPU, and display options available. It therefore offers the same gaming and visual experience but for much cheaper prices to be an easier recommendation even for enthusiasts.