Final answer:
Santiago and the merchant girl are different in several ways. The merchant girl makes Santiago feel a new sense of love and attraction, which relates to his fear of pursuing his personal legend.
Step-by-step explanation:
Santiago, the protagonist in The Alchemist, and the merchant girl, have several differences. Santiago is a young shepherd following his dream to find treasure, while the merchant girl is a vendor in a marketplace. The merchant girl makes Santiago feel a sense of love and attraction that he has never felt before. This relates to the obstacle of Santiago's fear of pursuing his own personal legend and leaving his comfortable life behind.