It is difficult to make a comparison that applies to the majority of Catholic colleges in terms of curriculum rigor in any subject. However, some general subjects that typically have a higher focus at Catholic college can be determined.
Religious and theology courses are typically prioritized at Catholic colleges. In accordance with the Catholic faith, these courses inform students and deepen their understanding of their faith. Students also explore other faith traditions, and learn about morality, context, and history. In some cases, this may mean that the curriculum for these classes is more rigorous than other classes, or other college's equivalent classes, but that is not necessarily true at every Catholic college.
Catholic colleges also typically place an emphasis on philosophy classes, service-learning classes, and social justice classes. These are classes that encourage critical and ethical thinking, explore themes about society, social justice, and societal issues, and give students opportunities to apply their education in real-life situations. These classes speak to the Catholic values of service, social justice, and caring for the whole person, thus it is common for Catholic colleges to require or "highly encourage" classes like these.
Common core classes, especially writing and analysis classes, are often given high priority as well. Catholic colleges aim to develop well-rounded individuals who are capable of critical thinking, good communication, and skilled analysis. The common core classes give students a base knowledge across a broad range of subjects, in theory increasing the avenues through which they can impact society.
Whether or not the emphasis on these subjects contributes to a more rigorous curriculum will depend entirely on the Catholic college itself. Sometimes a college is well-known for specific fields of study, and in those cases, classes within that field of study may have more rigorous curricula than other classes and majors. There is no general guarantee that will apply to every Catholic college. The best way to find out if there are subjects with more rigorous curriculum at a Catholic college would be to ask current or former students of the college itself.