Then we better steam up our wiki skills because I believe the wiki is wrong.
I think what they tried to explain is this:
Example 1, init.sqf
test = { player sideChat "wee"; sleep 10 };
spawn test;
player sideChat "wee2";
Example 2, init.sqf
test = { player sideChat "wee"; sleep 10 };
call test;
player sideChat "wee2";
In example 1, the player will read in sidechat "wee" and immediatly followed "wee2" (or possibly the other way around, because the spawned code has a slight delay)
In example 2, the player will read in sidechat "wee" and 10 seconds later "wee2"
In example1, the script continues processing immediatly after the spawn, because you spawn the test code in another "thread"
In example2, the calling script executes and waits for the call to complete, before it continues processing within the file, exactly the same as if there really was written in this script: player sideChat "wee"; sleep 10;
Basicly, the below is exactly the same as Example2, except that you don't use the test variable to store the code:
player sideChat "wee";
sleep 10;
player sideChat "wee2";
(except that in the original Example2, test { } block is another scope)