A tidal wave is a periodical event that is caused by the relative positions of the system Sun, Earth, Moon. It is caused by gravity force, and by the fact that the Earth is not a geometrical point, meaning that it has a radius greater than 0. The first to discover the reason of tidal waves was Isaac Newton (Mathematica Principia). Tidal waves are well known,easily predicted and have rise and fall period in terms of hours, so that their energy can be absorbed in a long time. A tsunami wave appears due to a catastrophic event in the water, like explosion, meteorite fall, earthquake; its reality is grounded as a special solution (soliton) to the wave equation; this special solution travels at high speed in the water, carrying a huge quantity of energy, and during its travel dissipates a very small fraction of its energy; that energy is almost completely dissipated when striking on the coast line, with a secondary catastrophic event, due to the very short time of the phenomena.

Tidal waves are predictable, caused by the tides. Tsunamis are caused by violent events. http://www.scienceandthesea.org/index.php?option=com_content&task=view&id=104&Itemid=10