What constitutes a book that’s been updated, revised, or expanded into a new edition? Enough of a change to the contents so that it's not quite the same book. Typically, this means significant rewriting and/or restructuring, new material added, outdated material removed, and so on. The book will feature a new preface, if it has one; and if there's a foreword, a new foreword as well. Each in its own way will situate this new and changed edition with respect to the previously published version. The book will also carry a new ISBN.
A book reissued with no changes, or only minor copyediting fixes, is a reprint. A book reissued with a new cover or other repackaging is a reprint.
Updated, revised, or expanded editions are typical of informational nonfiction. Works of fiction and narrative nonfiction are not typically revised and updated, except under special circumstances such as the release of a new critical edition or translation.
The terms small press and independent (or indie) press are sometimes used synonymously.
An independent press is any house not associated with the Big 5 conglomerates or their imprints. When the two terms are used distinct from each other, “small” indicates annual sales of under $50 million and generally fewer than ten books published a year. When used as distinct terms, the relationship is this: a small press is always independent, but an independent press is not always small.