Your image has good quality or you need a true-to-pixel upscale with no changes to the original photo - choose the classic Upscale.
Your image's quality is not good, has noise, blocks or you need more than 8x upscale - choose the Ultra Upscale.
You need up to 16x upscale, you need added details to the image, you need improved quality - choose the Ultra Enhance option.
Read more here.