There are many possible varieties of Catadioptric Cassegrain telescopes. Most of them attempt to save on the manufacturing cost by using spherical optics. Spherical mirrors rather than parabolic or elliptical or hyperbolic ones are much easier to make and less expensive. The same applies to lenses.
Here are several possible versions. I compare them with one another. However, my conclusion as to their performance is only valid for these particular examples and should not be generalized to all such scopes. For example, the Maksutov is a well-understood and quite effective design that nearly always produces a superb image despite the rare poor example shown in this video.
Here are my videos ...