No, they are two different things.

The Eye of Truth grants you the ability to see certain invisible things throughout the Bottom of the Well, the guide through the desert, and the Shadow Temple. You can't speak to truth stones with it.

The Mask of Truth is a reward for completing the Happy Mask miniquest. To get it, you will need to sell all the masks in the Happy Mask Shop before the Happy Mask Salesman will offer you an assortment of four new masks - this included - and the masks previously sold. Unlike the Eye of Truth, you cannot see invisible/unseen things, nor does it help you through the desert.

Might be a bit off (apologies)-

1) Kafei mask - sell to the guard near Death Mt gateway.

2) Skull mask - sell to the Skull Kid in the Lost Woods on top of the tall log/podium where you play Saria's song with him.

3) Redead mask - sell to the kid in Kakariko Village graveyard (appears only during the day, pretending to be Démpe).

4) Bunny hood - sell to the marathon guy running around Hyrule field. All day NPC.

Once you've sold all four masks, you can now borrow any mask for free, and four new masks are added: Goron mask, Gerudo mask, Zora mask and the Mask of Truth, which can be used to speak with the truth/time telling stones scattered throughout the game for secrets and tips.