Clauses [lex] through [cpp] describe the C++ programming language. That description includes detailed syntactic specifications in a form described in [syntax]. For convenience, Annex [gram] repeats all such syntactic specifications.
Clauses [language.support] through [thread] and Annex [depr] (the library clauses) describe the C++ standard library. That description includes detailed descriptions of the entities and macros that constitute the library, in a form described in Clause [library].
Annex [diff] summarizes the evolution of C++ since its first published description, and explains in detail the differences between C++ and C. Certain features of C++ exist solely for compatibility purposes; Annex [depr] describes those features.