Difference in mime-type in form PHP

Question

I would like upload .docx, but

In $_FILES['field']['type'] is application/vnd.openxmlformats-officedocument.wordprocessingml.document , but in mime_content_type() return application/zip

Why these types are diffrent? Which is good?

Answer 1

The DOCX format consists of a number of different files all wrapped up in a zip file. The software you are using is examining the file, seeing it is a zip file and reporting it with the standard MIME type for zip.

"Good" is somewhat subjecting, but application/vnd.openxmlformats-officedocument.wordprocessingml.document is probably better as it is more specific.