The document compares key differences between Spanish and English language structures that would cause errors for a Spanish-speaking English language learner. It provides examples of errors made by Luigi, a 27-year-old student from the Dominican Republic studying in English. Luigi's errors demonstrate issues with subject-verb agreement, tense, articles, prepositions and word order that stem from applying rules of Spanish syntax to English. The summary identifies that the learner's "interlanguage" leads to these differences being sources of error.