This study investigates variation in article use by Korean secondary school students of English. The study shows how two different tasks affect variation with respect to article types (a, the, and zero), proficiency level and the semantic feature, specificity. One task, a wide domain task, focused on grammar in general and the narrow domain task focused on articles. The statistical results showed that the subjects performed significantly better on the narrow domain task than on the wide domain task. The subjects showed significant differences among the three articles in the wide domain task, while they did not in the narrow domain task. The subjects performed significantly better with non-specific DPs (Determiner Phrases) than with specific DPs in the wide domain task, but reversed results were revealed in the narrow domain task. The present study presents some finding that grammatical domain plays a role as a variable for variability and shows that different tasks on the same research topic may produce different findings.