Constraints - brief commands from start to end

Clock commands:

Creating clock:
Setting clock attributes:
Defining relationship b/w clocks: 

create_clock
clock_input_transition
clock_uncertainity
clock_inter_clock_uncertainity
create_generated_clock
set_clock_groups  -from CLK1 -to CLK2  asynchronous


1. What is the difference b/w commands? Are they exactly same?
    a) set_clock_groups  -from CLK1 -to CLK2  asynchronous
   b) set_false_path  -from  CLK1  -to  CLK2
       set_false_path  -from  CLK2  -to  CLK1