Clock generation using Blocking or Non blocking statements

Hi all,

Consider the following two blocks of code


initial #1 clk1 = 0 ;
always @ ( clk1 )
#10 clk1 = ~clk1 ;

initial #1 clk2 = 0 ;
always @ ( clk2 )
#10 clk2 <= ~clk2 ;


What is the difference between the following two block of statements