ControlNet is a neural network structure to control diffusion models by adding extra conditions. Inference is controlled by an input image and respective ControlNet model. These ControlNet models include openpose, depth, anime lineart, and more.
Reference Control is a feature of the ControlNet extension, but is technically not related to ControlNet. https://github.com/Mikubill/sd-webui-controlnet/pull/1235
Paper: https://arxiv.org/abs/2302.05543
GitHub: https://github.com/lllyasviel/ControlNet
Web UI extension: https://github.com/Mikubill/sd-webui-controlnet