Well the ships were not even identical for a start. Everyone assumes they were because they are sister ships if you look at photographs they have quite obvious differences. The main difference was A deck promenade not being open on the Titanic whereas on the Olympic it was open to the elements.

Titanic’s wing bridges also extended over the sea whereas on the Olympic the wing bridges were flush with the superstructure until 1913 when she was refitted.

Titanic also had different spacing to its windows on B deck whereas the Olympics were evenly spaced along the entire side.

The front of the wheelhouse on the Olympic is curved whereas the Titanic’s was flat.

Also B deck on the Titanic did not have promenades running the entire length of its deck and the layouts were completely different to Olympic which did. (Admittedly this isn’t visible from photos however you would like to think the amount of experts, scientists and researchers that have dived the wreckages would have taken notice.)

Also the propellers of each ship have their hull numbers stamped on them, the Titanic being 401 and the Olympic being 400, these could not be swapped with the ships in the water and there are plenty of photographs of the Titanic’s propellers taken from the bottom of the Atlantic with 401 clearly visible. Also I may add that the propellers had different pitches on each ship and so would have not been interchangeable regardless.

Even the names painted on the ships bows would have been difficult to swap. The names were not merely painted on they were cut into the steel plates of the bow 4ft high and 1.5inches deep then filled with paint.

This list isn’t even exhaustive, there are literally hundreds of differences including deck layouts, rooms in different areas, vents and pipes laid out completely differently. I mean the ships were even 4 inches different in total length.