Shareholders are effectively owners; debenture-holders are creditors.
Shareholders may vote at AGMs and be elected as directors; debenture-holders may not vote at AGMs or be elected as directors.
Shareholders receive profit in the form of dividends; debenture-holders receive a fixed rate of interest.
If there is no profit, the shareholder does not receive a dividend; interest is paid to debenture-holders regardless of whether or not a profit has been made.
In case of dissolution of firms debenture holders are paid first as compared to shareholder.