In the passage, the words and phrases that indicate comparison between the Leaning Tower of Pisa and the Washington Monument include "BOTH," "LIKE THE LEANING TOWER," and "BOTH STRUCTURES ATTRACT MANY TOURISTS EACH YEAR." These words signal that the author is highlighting similarities between the two monuments.
On the other hand, the contrasting elements are shown through phrases such as "BUT THE PURPOSES OF THE BUILDINGS WERE DIFFERENT" and "ONE WAS ERECTED AS A CHURCH BELL TOWER, WHILE THE OTHER HONORED A FOUNDING FATHER." These phrases emphasize the differences between the two structures.