Premiere Elements - Backiup

As Bob pointed out.

Project files and media files (preferable to a different drive)

There is a choice in the File menu called Project Archiver.  It may accomplish what you want.  Within the function there are options for what you want to include.  

That said, I don't use it.  Instead I make a dedicated folder for each project.  I put copies of source media in it along with the project files and scratch disks.   Because I use a fast SSD, it optimizes performance but also makes backups or copies easy.   I can simply copy the entire folder to any backup media.  

Backup the project files and the media files.

The preview files will be recreated if needed when the backup project file is opened.

What I do (Windows 10)

Drive C for Windows and all programs

Drive F for project and output files (I always output to ISO before writing to DVD)

Drive G for video and picture input files... a different folder for each project

Every time I start a project I set my project and work files to F:\Adobe
(F is MY drive for temporary files, your drive letter may be different)
I work in EXPERT view to be able to control every aspect of my project
Click EDIT and then PREFERENCES and then SCRATCHDISKS
I set every one of the options to F:\Adobe
PrE then automatically creates sub-folders as needed
F:\Adobe\Adobe Premiere Elements Audio Previews
F:\Adobe\Adobe Premiere Elements Captured Audio
F:\Adobe\Adobe Premiere Elements Captured Video
F:\Adobe\Adobe Premiere Elements Video Previews
F:\Adobe\Encoded Files
F:\Adobe\Layouts
F:\Adobe\Peak Files

When I am done with a project I copy the project file and source folder to a folder in a 'bare' Sata drive in an external dock

https://www.amazon.com/StarTech-com-External-docking-station-drives/dp/B00U8KSLA8/