Why is memory management in macOS more efficient than in Linux? I have been a Linux user for four years. Recently, I have been using macOS and I see it has very efficient memory management compared to Linux.

For example, here is a description of the documents/apps I have open on a Mac Mini i5 1.4 GHz 8GB RAM 500 GB HDD @ 5400 RPM:


40 pdfs 
Blender
PowerPoint 
Photos
iTunes
12 Safari tabs
QuickTime video
Terminal
Maps
Sublime Text
Calendar


With these open the Mac showed 5.91 GB of RAM used. 

My question is: What's different about the Mac that on Linux I can't even open half the apps with a machine with the same amount of memory and HD?
Most of the efficiency comes from large blocks of read-only memory being shared between applications. Most graphical Mac applications use common frameworks. Where possible macOS only loads one instance of a framework into memory.

For more about macOS memory management and organisation see:


How does memory management work in Mac OS X?
What&#39;s the difference between Real, Virtual, Shared, and Private Memory?