PDFs and Word documents solve different problems. This guide explains which to use for contracts, resumes, reports and sharing.
The short answer
Use DOCX when you will edit. Use PDF when you will not. That is 90% of the decision.
Why PDF exists
PDFs render identically on every device. If you send a contract, invoice or resume as PDF, what you see is what they see.
Why DOCX exists
DOCX is for collaboration. Multiple people can comment, track changes and edit. It is the wrong format for final delivery.
The workflow most pros use
Draft in DOCX. Export to PDF when sending externally. Keep the DOCX as your source.