Where the return actually comes from
A structured note is not a fund and does not hold the reference asset. You do not own the index the note tracks. You own a promise from the issuer to pay an amount calculated from that index.
That distinction drives most of what follows. The bond component is what makes the note a debt of the issuer. The embedded derivative is what makes the payment depend on something other than an interest rate. Splitting the product into those two parts is the fastest way to see what you are exposed to.