hii jyoti… as discuss by all fork is used for replicating the signal where as splliter is to divide the power level .. for example if you are using a 1:2 splitter you will get a power/2 at each output port of the the spillter as compared to input ..where is in fork u will get same power level .. one for thing i want to add that splitter is generally used in PON(Passive Optical Network)… hope you are getting the point