The difference to the Schmidt-Cassegrain: the Maksutov has a meniscus-shaped lens on the lens aperture and no Schmidt plate. This lens design was created by the Russian optician Maksutov.
But what are the benefits? With a uniform thickness of the lens, the system displays only slight chromatic aberration. In addition, it corrects the spherical aberration created by the primary mirror.
The system’s secondary mirror is vapour-deposited on the rear side of the meniscus lens. Therefore there is no secondary mirror spider vanes which would bend the light. Since the secondary mirror is small there is only a small amount of shadow. This means: very good contrast, comparable to that of a refractor.