The options-multiplier tells you the contract size; the deliverable tells you what shows up in the account. For a plain equity option the deliverable is 100 shares of the underlying. For an index-option it is a cash amount. For an adjusted-option it can be almost anything.
Checking the deliverable before trading an adjusted line is not optional. The premium may look cheap only because the contract controls far fewer shares than you assume.
Example: XYZ pays a special dividend and the deliverable becomes 100 shares of XYZ plus $250 cash. A $52.50 call that used to be worth $250 at $55 now settles differently, and the break-even you calculated from the screen price is wrong until you re-do the arithmetic on the real deliverable.
Related: adjusted-option, corporate-action, options-multiplier, exercise-settlement-value