WoWInterface - Difference between /target and /targetexact

/target will target the first thing that matches what you put after it, but /targetexact will only target exactly what you put after it.

For example, let's say you are surrounded by 10 neutral npcs named "Billy" and a boss named "Billiam". /target Bill will target any of these 11 npcs with no guarantee who, but /targetexact Bill will do nothing because there is no npc named Bill nearby.

If you are familiar with Lua, here's the two functions that these commands call:

Lua Code:

SecureCmdList["TARGET"] = function(msg)
    local action, target = SecureCmdOptionParse(msg);
    if ( action ) then
        if ( not target or target == "target" ) then
            target = action;
        end
        TargetUnit(target);
    end
end
 
SecureCmdList["TARGET_EXACT"] = function(msg)
    local action, target = SecureCmdOptionParse(msg);
    if ( action ) then
        if ( not target or target == "target" ) then
            target = action;
        end
        TargetUnit(target, true);
    end
end

And the function they use: https://wow.gamepedia.com/API_TargetUnit
(TargetUnit is defined in the C portion of WoW, not reasonably available to the public)