sims3package shows up for sims4 package

@hhumes316  Did you install S3PE or another program designed to open or modify .package-based content?  If you used one to open Sims 3 mods or cc in .package-based form, then Windows may have created an association between that program files with the .package extension.  Windows doesn't distinguish between Sims 3 and Sims 4 content; anything with a certain file extension gets the same association.

As for whether the files should work in your game, there's no harm in trying.  Just don't save your progress.  But as long as you didn't open and modify the Sims 4 files, they should be fine.  They're read by the game, not Windows, and each game can read its own files properly regardless of what association Windows has set.