Original sentence: As a datatype, a class is usually considered as a compile-time construct.Many languages distinguish this kind of run-time type information about classes from a class on the basis that the information is not needed at run-time.Some dynamic languages do not make strict distinctions between run-time and compile-time constructs, and therefore may not distinguish between metaobjects and classes
Edited sentence: As a datatype, a class is a compile-time construct.But these should not be confused with classes, as these often do not include all information about classes due to concerns with space consumption