Broad: it covers the main aspects of the topic without going into unnecessary detail.
Neutral: it represents viewpoints fairly and without bias.
Stable: it does not change significantly from day to day because of an ongoing edit war or content dispute.
Images: it is illustrated, if possible and relevant, by images with acceptable copyright status and fair use rationales where necessary.
A featured article exemplifies our very best work and has the following attributes:
High and reliable quality—(a) engaging prose of a professional standard; (b) comprehensive coverage of major facts, details, and context; (c) factual accuracy, with citations for verification against reliable sources; (d) neutral presentation of viewpoints; and (e) stable content.
Style compliance: it follows the entireManual of Style and has—(a) a concise, summarizing lead; (b) a substantial but not overwhelming table of contents; and (c) consistently formatted inline citations.
Media. It has images in accordance with image use policies; in particular, they have acceptable copyright status and fair use rationales where necessary.
Length. It stays focused on the main topic without going into unnecessary detail.
Both criteria require: compliance with the general policies regarding content for all Wikipedia articles; avoidance of unnecessary detail; stability; neutrality; factual accuracy and verifiability; and acceptable copyright status for media.
Neither has absolute length requirements, although featured articles tend to be long; one of the original purposes of the GA process was to recognize short articles of good quality.
Featured articles must be our very best work; good articles meet a more basic set of core editorial standards and are decent.
A good article must be well written; a featured article must have an engaging, professional standard of writing.
A good article must be broad; a featured article must be comprehensive. The "broad" standard merely requires coverage of the main points; the "comprehensive" standard requires that no major fact or detail is omitted.
Featured articles are usually subject to greater scrutiny in regard to factual accuracy and verifiability. In particular, the inline citation requirements are stricter with featured articles.
Good articles are generally not required to be as well-illustrated by media.