Moria, Sauron, and the Balrog

[Olmer]

Originally Posted by Fenir_LacDanan

Oh, and a deciever IS a liar, they are one and the same thing.

No, they are not. It's a big difference between this two words.
You can deceive without lying just by withholding some information. (Usual telemarketers ruse )
But you can't lie without deceiving.
In a way a deceiver is a liar, but it not the same thing according to the law.
So, Forkbeard's depiction of Sauron's tactic ( Saying X and doing X, but along comes Z and Y, which he "forgot" to mention) is more in tune with his name : Sauron the Deceiver.