Ecologists can't measure the whole population so instead they measure and area say a square mile and count how many of X there are. Then for this particular region they can easily estimate the amount of X's by multiplying the total number of square miles by the number of X's they found in that 1 square mile
The difference between the two is simple diffusion moves molecules downwards instead of upwards and infacilitated diffusion is the opposit, simple diffusions also can be passive (no clue if that makes sesnse) but facilitated diffusion is a more active process requiring energy you could technically look this up for the answer and find the same thing just more explained.
the media says: "In simple diffusion, molecules move down the concentration gradient but <span> molecules move up the concentration gradient. </span>Simple diffusion<span>is passive but </span>facilitated diffusion is an active process that uses energy." all u have to do is look up "<span>Simple diffusion and Facilitated diffusion" and right at the top itll give u an answer</span>