Unlike in Romeo & Juliet, in West Side Story Tony does not hear Maria's inmost thoughts as Romeo does when hiding below Juliet's balcony. Instead, he calls out for her and is actively seeking her.
In the "What's in a name?" section Juliet looks past Romeo's name to see him for who he really is. This is parallel to West Side Story. Tony and Maria discuss the race problem (this is different from Juliet's exploration of the problem in a soliloquy). Tony looks past her race and loves Maria.
Juliet is worried about guards finsing Romeo. Maria is afraid of waking her parents and of Bernardo finding Tony.
Romeo's reaction to Juliet's worries, "And but thou love me, let them find me here..." is very similar to Tony's reaction to Maria's worries.
Maria and Tony don't spend time discussing their love like Romeo and Juliet.
"Tonight, Tonight" - mentions stars, a prominent feature in Romeo & Juliet.
Exchange between Romeo and Juliet similar to this song. Song addresses stars, and juxtaposes the earthly and the transcendental, similar to what Shakespeare does in Romeo & Juliet.
Tony and Maria do not discuss marriage like Romeo and Juliet.
Instead of the Nurse calling, Maria's father calls.
Juliet saying "With repetition of my Romeo's name" is much like Tony repeating Maria's name.
