The Titanium Drill is a Hardmodedrill, and is the drill alternative to the Titanium Pickaxe. Appearances and sounds aside, the two tools are nearly functionally identical. The drill, however is half a second faster. But, unlike pickaxes, most drills cannot be reforged with size, speed, or knockbackmodifiers.
Early into Hardmode, it is usually preferable to save Titanium for armor and weapons, as the Titanium Drill does not allow mining any new blocks that the Mythril and Orichalcum pickaxes and drills would not mine.