safety mode and standard mode

I want to know about Fail safe modules..

What is the difference betweensafety mode andstandard mode?

The basic difference between the standard mode and the Failsafe mode of the PLC is special functions. In fail safe mode you can use various functions as wire break of inputs etc. which is not present is standard mode, But keep in mind fail safe programming is completely different from standard programming, while doing programming you should have good knowledge of safety circuit of the application.