Many standardized reading tests yield separate scores for vocabulary and comprehension. Sometimes the vocabulary and comprehension scores for a given student are more or less (if not exactly) the same. In other cases, one is substantially higher than the other.
Duffelmeyer, F. A. (1981). A Comparison of Average Readers at Different Grade Levels. Reading Horizons, 21 (2). Retrieved from http://scholarworks.wmich.edu/reading_horizons/vol21/iss2/12