Neural network would be the most technically accurate given what they've announced so far.

There's no information on if it's a diffusion or transformer architecture. Though given DLSS 4.5 introduced a transformer for lighting, my guess would be that it's the same thing just being more widely applied. But the technical details haven't been released from anything I've seen, so for the time being it's being described as "neural rendering" using an unspecified neural network.

https://www.nvidia.com/en-us/geforce/news/dlss-4-5-dynamic-multi-frame-gen-6x-2nd-gen-transformer-super-res/

Generative AI is a decent catch-all that I think would apply to this.

Another good option is "machine learning" or ML, but that's fallen out of favor cause it doesn't sound as impressive as AI. But really it's teaching a machine to do a specific task. It's not intelligent, it's just that we don't understand how it learns.