DLSS - Deep Learning Super Sampling. It's an nvidia tech that renders the game at a lower resolution than native (e.g., game renders at 1080p with a 4k native resolution), and then they use an interpolation algorithm to reconstruct the image back to native resolution. This is cheaper from a hardware perspective than full native rendering. At native 4k, you might be able to squeeze 40-50 FPS out of the hardware, but with DLSS you can squeeze 70-80 out of it by rendering at a lower res and then reconstructing back to native. As the algorithm in DLSS 2.0+ has improved, you end up with image quality very close to native, or sometimes better than native image quality. Downside is it only works on RTX cards.

DLAA - Deep Learning Anti Aliasing. Basically DLSS, but you render at native resolution and use the interpolation algorithm as your anti-aliasing technique. Is more costly than the temporal anti-aliasing found in most games today, but provides superior image quality.

FSR - Fidelity FX SuperResolution. AMD's upscaling technology that they use to gain better performance. The game renders at a lower resolution and then uses a spatial upscaler and (depending on developer implementation) a sharpening filter to scale the game back to native resolution. Upside is it works on all GPUs. Downside is image quality - it's a simple upscaler, no reconstruction. Inner surface detail becomes blurry, and if the game's anti-aliasing isn't great, it upscales the aliasing on edges and they look bad.

RTGI - Ray Traced Global Illumination. This is using ray tracing to calculate bounce lighting within a game environment to provide realistic indirect lighting.

RTAO - Ray Traced Ambient Occlusion. This uses ray tracing to accurately create occlusion shadows within an environment, ensuring that shadowing interacts appropriately with direct and indirect lighting.