What's the different b/w storm surge and tsunami?

Storm surges are created by storms and tsunamis by underwater earthquakes, but the biggest differences of all are the waves themselves. Storm surges are high waves (~15-20m in height) with a fairly long wavelength (usually about a few 100m) and travel at speeds up ~100km/h. Tsunamis are much worse. They have wavelengths over 150km (which makes them just a huge wall of continuously coming water), heights of about 4m, but travel at high speeds, usually 500-800km/h.

A storm surge, like any other wave caused by wind only affects the surface of the ocean. The wave travels through the surface waters and the height of the wave, the distance from the crest to the trough can be measured. Storm surges on top of high tides can take water some distance inland.

A tsunami is a wave that extends through the full depth of the ocean, not just the surface waters. On the surface in the open ocean it is hardly noticeable and it travels very fast through the water. As the ocean floor shoals, the wave is compressed and starts piling up the water which then pours inland. Storm surges can be devastating but they are nowhere near as powerful as tsunamis.

storm surge: rise in sea level due to a drop in pressure from an intense storm

Tsunami, a large wave of water rushing over land caused by a submarine earthquake, in which the motion of crustal plates displaced a large volume of water