There are several possible contexts that could describe a difference of rational numbers. Some examples include:
1) In a mathematics problem, finding the difference between two rational numbers: For example, finding the difference between 3/4 and 1/3.
2) In a real-life situation, comparing the differences in measurements: For example, comparing the difference in weight between two objects, where the weights are represented by rational numbers.
3) In a statistical analysis, comparing the differences in data sets: For example, analyzing the difference in test scores between two groups of students, where the scores are represented by rational numbers.