i need to know the 2 kind of forms , which one is More functional ?

i need to know the 2 kind of forms , which one is More functional ?

 1) <form></form> ,  

 2) <?php echo form_open(''); ?><?= [b]echo form_close();?>[/b]


again i need to ask which one is more functional , and i need input type date how to use it in 2nd one form ?