Why do htop and gnome-system-monitor display the amount of RAM differently?

Question

linux

Answer 1

I will assume that gnome-system-monitor shows the amount used + buffers + cache , and your htop only shows used. Set up htop like mine (in the Mem part) - it will be more interesting. :)
Upd. xolst9 ,

but not cache (+cache)

Perhaps you are right, crossed out in the answer.

Answer 2

Because one outputs in GB and the other outputs in GiB