How does the steam turbine differ than the gas turbine?

The words itself is self explanatory..steam turbine using steam to drive the shaft and blade while in gas turbine,exhuast from combustion in the combustion is used to drive the turbine section..Power generated depends on the design of the steam turbine itself..my previuos work place only produced10MW..

STEAM TURBINE RUNS  BY STEAM .HERE WATER IS THE MEDIUM FOR GENERATING THE STEAM.HERE INPUT ENERGY IS COAL.IT REALEASE  HEAT ENERGY BY OXIDATION OF OXYGEN THEN TRANSFER HEAT THROUGH MEDIUM THEN FORM A STEAM .

GAS TURBINE RUN BY GAS.HERE COMPRESSED AIR IS USED AS A MEDIUM FOR GENERATING GAS .HERE INPUT IS GAS INJECTED THROUGH THE BURNER AND THEN GAS IS LIGHTED UP.

In short, steam turbines do not come in contact with fuel, and gas turbines do

Well there are some few differences between the two as well as some similarities. 

So lets start with the common term "turbines"

Turbines are nothing but machines which are used to harness energy (in the form of pressure) from a source and convert it into mechanical work.

For a gas turbine, this pressure is increased throughout the compressor section and into a combustion section that uses a fue "either gas hence the name or even liquid fuel". It uses the Brayton Cycle as its thermrodynamics principle.  

Steam Turbines use energy of steam, which is expanded through aptly designed blades in turbine, finally giving work output. It uses Rankine Cycle principle.

Expansion is the process that lead to converting power for both Gas turbine and Steam turbines. Basically decreasing the pressure and increasing the volume of steam or gas, which converts its pressure energy into kinetic energy (or mechanical work) through turbine blades. 

In short, steam turbines do not come in contact with fuel, and gas turbines do. 

 

Also gas turbine use to provide electrical power low range than steam gas turbine max power generated250 mega watt" from one gssturbine" , steam turbine starts froom300mega watt

 

totally different operation principles..
steam turbine produces shaft power from either pressure difference of the inlet and exhaust steam (reaction turbine) or velocity difference of the steam (impulse turbine).
there is no ignition/ compression.
gas turbine takes air from atmosphere, compress it and mixes it with fuel gas inside combustion chamber and ignites it to make a high temperature exhaust gas flow.
this flow is then used by the turbine to produce shaft power.