Wordpress is an online platform and an open source website builder that is written in PHP. The platform supports support mysql or php and probably the easiest and most powerful blogging and website content management system (or CMS) today.
Weebly is a web-hosting service featuring a drag-and-drop website builder. This platform uses uses CSS and html codes. It does not support PHP or mysql.
Coming back to our question, is it possible to upload Wordpress Theme to Weebly site? The answer is big NO though the vise versas works perfectly.