What is differents between RealESRGAN_x4plus.pth and RealESRGAN_x4plusD.pth

[dumppool]

In the document, it mentioned that:
_Download pre-trained models into experiments/pretrained_models.
RealESRGAN_x4plus.pth:

wget https://github.com/xinntao/Real-ESRGAN/releases/download/v0.1.0/RealESRGAN_x4plus.pth -P experiments/pretrained_models
RealESRGAN_x4plus_netD.pth:

wget https://github.com/xinntao/Real-ESRGAN/releases/download/v0.2.2.3/RealESRGAN_x4plus_netD.pth -P experiments/pretrained_models_
What is differents between RealESRGAN_x4plus.pth and RealESRGAN_x4plusD.pth ?