Moving an experiment from one project to another is possible between projects that contain same (and additional) users.
When moving an experiment, entire content i.e. all tasks are transferred. This includes all comments, results, activities, and tags as well.
To move an experiment to another project select Move action from the drop-down menu (see the image below).
To learn more about how to create new experiments, how to copy or move them between different projects watch this video tutorial.