The document discusses key differences between the Vietnamese and English languages and provides a case study of a Vietnamese student named Sam Johnson. Some key differences highlighted include: Vietnamese is a tonal language with six tones represented by diacritics, while English is not tonal; Vietnamese does not use suffixes but English does; and Vietnamese has one form of verbs while English has multiple forms. The case study notes Sam struggles with English verb tenses and endings, vocabulary, and nouns. It provides recommendations for Sam such as focusing on verb endings and minimal pair activities.