Debenture
is secured liability to company, it redeemed particular time and it fixed
particular interest rate. Bond is one of the liabilities of the company but it
has no security than debentures and it has no premium like debentures. Bond is a secure loan where as
debenture is unsecured, usually corporate issue debenture to secure their
capital. Though both bond&debenture may be for perpetual time, but it
depends on the issue.

Another difference is bond holder has a greater claim on an issuer's income than a shareholder in the case of financial distress (this is true for all creditors) but debenture holders usually does have greater claim than shareholder.