There's a "Preface to the Second Edition" near the front, which has a summary of changes. Main points are: 1) notation was overhauled, 2) Chapters 2-8 were reworked to only use tabular methods, with function approximation introduced later; 3) the function approximation coverage is then greatly expanded in the second section of the book (Chs. 9-13); and 4) new chapters 14-15 on connections between RL and psychology and neuroscience.
The scope is generally about the same though, perhaps because it's intended to be used as a single-semester textbook, so there isn't a big expansion into areas of RL other than those covered in the first edition (e.g. POMDPs are only briefly mentioned).
The scope is generally about the same though, perhaps because it's intended to be used as a single-semester textbook, so there isn't a big expansion into areas of RL other than those covered in the first edition (e.g. POMDPs are only briefly mentioned).