CCs have a VERY different mission that four year colleges. At many CCs, the assumption is that the intro bio class is for students who did not take any higher level bio course in high school. At four year colleges, they assume that a student has at least take college prep bio in high school. If the course is for bio majors, they assume that the students have taken at least honors level bio, and that some have taken AP bio and want to repeat it.
The level of intro bio for bio majors at four year colleges is generally equivalent across a very wide swath of colleges. The difference in the intro classes is how well the students are prepared, and how well they do. The big difference in class depth and width comes in the more advanced classes. There can be a pretty large difference in the rigor of a 300 level course at different colleges.
Of course, there are also differences which are not related to rigor, per se, but can determine how difficult a student finds a class. A class at a LAC can be very different than a class covering the same material at a larger university, even if the two cover the same material at the same depth. Some students will find the LAC class to be more difficult, which others, who are equally academically talented, would find the university class to be more difficult.