Add to project option allows you to create your own selection of locations or pictures for your particular project. A separate page will be created with your short listed locations or pictures. On that page you will have an option to send this project to your partners or friends by filling in the online form. Your partner or friend will receive an e-mail with the direct link to your project. They will not need to register to be able to access your page. You and the people you invite will be the only ones able to access this page and leave comments. Other users of the website will not be able to find your page.
Create new project allows you to start selecting pictures for a new project you have in mind. You will be able to save the selection here and come back to it later to change it or add more pictures to it. You will also be able to send and invitation to your partners or friends to view your selection whenever you are ready to share it.
Add to existing allows you add more pictures to your previously created selections/projects and send them to partners or friends.