What distinguishes redeemable debentures from irredeemable debentures?

Redeemable debentures are repaid at the end of a specific period, while irredeemable debentures have no repayment period

The primary distinguishing feature between redeemable debentures and irredeemable debentures is their repayment structure:
Redeemable Debentures: These debentures are repayable at the end of a specific period, either in a lump sum or in installments, during the lifetime of the company. The company commits to repaying the principal amount to debentureholders on or after a predetermined date.
Irredeemable Debentures: Irredeemable debentures, also known as perpetual debentures, do not have a specific repayment period mentioned. The company does not provide any undertaking for the repayment of the money borrowed through these debentures. Instead, they are typically repayable on the winding-up of the company or on the expiry of an extremely long period, often making them akin to perpetual debt.