A.13.4 Between Versions 3 and 4
61 new built-in objects have been added, some of whose names may conflict with names already being used.
N now yields a machine-precision zero rather than an exact zero.
FullOptions has been superseded by AbsoluteOptions, which yields results in the same form as Options.
Element[x, y] or now has built-in evaluation rules.
The symbols I and E are now output in StandardForm as (\[ImaginaryI]) and (\[ExponentialE]) respectively.
A new second argument has been added to CompiledFunction to allow easier manipulation and composition of compiled functions.