Confusion with call syntax

[Taugeshtu]

Hi. I can't help but noticed that sometimes stuff is done through cRoot:Get(), or like so:

Code:

local root = cRoot:Get()
local world = root:GetDefaultWorld()

And sometimes it's like cPluginManager.AddHook( cPluginManager.HOOK_PLAYER_LEFT_CLICK, OnPlayerLeftClick )

Can someone please explain me the sacred meaning behind all this? Because I'd like to know in my mind in which case what should be used, I don't like the idea of having to ho through 5 different previous sources to find my case and using it.