An exchangeable note is a debt security that the holder may exchange, at a certain price, for common stock in a company which is not the same company as the issuer of the note. The number of shares the holder receives and the price of those same shares is determined at the time the exchangeable note is issued.
A convertible note is a debt security that allows the holder to convert it into shares of the company that issued the notes. The notes are usually convertible at their maturity date. The holder of a convertible note receives interest on a six month basis and can sell the note in the open market.
The main difference between a convertible note and an exchangeable note is that the issuer decides when a an exchangeable note is exchanged for shares whereas with a convertible note the note is converted into shares or cash on the maturity of the note.