Cheque and DD, both are negotiable instruments and to be 
honored.  But the basic diffrence is, check will be issued 
by an account holder and whereas DD can be issued by a 
banker only.... Cheque may get rejected due to lot many 
reasons....but DD will not get rejected if u present.  
(Some DDs were not accepted by Scheduled commercial banks, 
as the DDs were issued by some problematic Co-op banks. 
There are some other differences too.