A semicolon ! Kidding ............ . Let me put it is code snipet and tell you .
1.
@posedge clk
a = 0 ;
// here the value of a is assigned to 0 after the event of posedge of clk .
2.
@posedge clk;
a = 0;
// Here value of a =0 after the event posedge of clk.
A semicolon ! Kidding ............ . Let me put it is code snipet and tell you .
1.
@posedge clk
a = 0 ;
// here the value of a is assigned to 0 after the event of posedge of clk .
2.
@posedge clk;
a = 0;
// Here value of a =0 after the event posedge of clk.
If you only contian a assignmets in one block, there's no difference for these two ways; however, if there are more than one block which will assign some values to a with these two methods, then the result may be different.