Export an individual file
Export file saves the active source file with its extension. For example, an active main.tex exports as TeX. This does not bundle the other files, bibliography, or figures from a multi-file project.
Keep the complete project
Export project (.zip) packages the project sources for a source-based workflow. Save a copy (.ltxs) creates a portable Paper Studio document for continued editing. Choose a project format when you need more than one active source file.
Check the destination
A PDF is the typeset result; TeX and ZIP are editable source, not a guarantee that another compiler has the same packages or fonts. Review the receiving publisher's requirements and compile the source in the destination environment when necessary.