Even if Marriott does not currently use the term "comparable" in its T&Cs, the travel industry widely uses the term "comparable" when referring to a substitute hotel that a guest is sent to when a guaranteed reservation cannot be honored.
For example, here's what
IHG has at its FAQ:
Why do we require a credit card for Internet reservations?
By securing your online reservation with a credit card, you are eligible for our Reservations Guarantee. If your reservation cannot be honored, the host hotel will provide a room at, and transportation to, another convenient and comparable hotel, and pay for telephone calls to notify family of the lodging change. The host hotel will also pay the full cost of the first night's lodging rate, plus tax. Any advance deposit will be refunded.
Even if Marriott does not use the word, there's still a reasonable exception that a guest will be walked to hotel of a similar category and quality.