difference between the absolute path and relative

It sounds like you're referring to the team space upgrade. For reference, you can find more information on that upgrade in the help center here.

On the Dropbox API, there are multiple ways to reference items in a Dropbox account. Exactly how you do so is up to you, and will depend on how you want your application to work. You can find more information in the File Access Guide.

For example, you may specify a path to a file by giving the full absolute path, including the names of any parent folders, such as "/folder_name/file_name.ext". You could instead specify that relative to that folder by id though, like "id:abc123xyz/file_name.ext" (where "id:abc123xyz" is the id of the folder). Check out the documentation linked above for more information.

For the team space upgrade in particular though, note that team folders are moved to the team space, and regardless of how you specify paths, you'll need to set the relevant root to access anything in the team space. I highly recommend reading the Team Files Guide for information on how to handle that.