You are in control of those functionalities because you decide the downloadable resolution and enable / disable the proofing feature.
The person who receives your Picter sharing link gets:
An overview of the images within the shared project
To preview a larger display version of all images in an easy to navigate gallery
If enabled:
Downloading the images of your project in the set resolution
Low resolution: 1500px
Original resolution: Up to 5000px
Proofing options for feedback on individual images