Differences from Titanic

The Olympic and Titanic were nearly identical, and were based on the same core design. A few alterations were made to Titanic and later on Britannic which were based on experience gained from Olympic's first year in service. The most noticeable of these was that the forward half of Titanic's A Deck promenade was enclosed by a steel screen with sliding windows, to provide additional shelter, whereas Olympic's promenade deck remained open along its whole length. The additional enclosed volume was a major contributor to Titanic's increased gross register tonnage of 46,328 tons over Olympic's 45,324 tons, which allowed Titanic to claim the title of largest ship in the world.[35]

Additionally, the B-Deck First-Class promenade decks installed on Olympic had proven to be scarcely used because of the already ample promenade space on A-Deck. Accordingly, Thomas Andrews eliminated this feature on Titanic and built additional, enlarged staterooms with en-suite bathrooms. It also allowed a Café Parisien in the style of a French sidewalk café to be added as an annexe to the À la Carte Restaurant, and for the Restaurant itself to be expanded to the Port-side of the ship. One drawback of this was that the Second-Class promenade space on B-Deck was reduced aboard Titanic.

A reception area for the restaurant was added in the foyer of the B-Deck aft Grand Staircase on Titanic, which did not exist on Olympic, and the main reception room on D-Deck was also slightly enlarged. 50-foot (15 m) private promenade decks were added to the two luxury parlour suites on B-Deck on Titanic, as well as additional First-Class gangway entrances on B-Deck. Cosmetic differences also existed between the two ships, most noticeably concerning the wider use of Axminster carpeting in Titanic's public rooms, as opposed to the more durable linoleum flooring on Olympic.

Most of these shortcomings on Olympic would be addressed in her 1913 refit, which altered the configuration of Olympic's First-Class sections to be more like those of Titanic. Although the A-Deck Promenade remained open for the entirety of Olympic's career, the B-Deck promenade was vetoed and staterooms added like those on Titanic, as well as a Café Parisien and enlarged restaurant. The 1913 refit also included modifications for greater safety after the loss of the Titanic, including the addition of extra lifeboats and the addition of an inner watertight skin in the hull along about half the length of the ship. An extra watertight compartment was added bringing the total of watertight compartments to 17. Five watertight bulkheads were raised to B deck. Along with these improvements there were many others included in the 1913 refit.

source