A.13.2 Between Versions 1 and 2
260 new built-in objects have been added, some of whose names may conflict with names already being used.
Accumulate has been superseded by FoldList; Fold has been added.
Condition (/;) can now be used in individual patterns as well as in complete rules, and does not evaluate by default.
The functionality of Release has been split between Evaluate and ReleaseHold.
Compose has been superseded by Composition.
Debug has been superseded by Trace and related functions.
Power no longer automatically makes transformations such as Sqrt[x^2]x.
Limit now by default remains unevaluated if it encounters an unknown function.
Mod now handles only numbers; PolynomialMod handles polynomials.
CellArray has been superseded by Raster and RasterArray.
FontForm takes a slightly different form of font specification.
Framed has been superseded by Frame and related options.
ContourLevels and ContourSpacing have been superseded by Contours.
Plot3Matrix has been superseded by ViewCenter and ViewVertical.
FromASCII and ToASCII have been superseded by FromCharacterCode and ToCharacterCode respectively.
Alias has been superseded by $PreRead.
ResetMedium has been subsumed in SetOptions, and $$Media has been superseded by Streams.
StartProcess has been superseded by Install and by MathLink.
Additional parts devoted to Mathematica as a programming language, and to examples of Mathematica packages, have been dropped from The Mathematica Book.