Final answer:
DNA contains the nitrogen base thymine (T) while RNA does not.
Step-by-step explanation:
The nitrogenous bases in DNA are adenine (A), guanine (G), cytosine (C), and thymine (T), while in RNA, the base thymine is replaced by uracil (U).
So, the nitrogen base that DNA has and RNA does not have is thymine (T).
DNA contains the nitrogen base thymine (T) while RNA does not.