Wikipedia:Compare criteria Good v. Featured article

A good article meets a basic set of editorial standards and is all around decent. It has the following attributes:

Well written: prose and layout are clear; it complies with the Manual of Style guidelines for lead sections, layout, words to watch, fiction, and list incorporation.
Accurate and verifiable: sources are reliable, listed, and cited; no original research, copyright violations, or plagiarism are present;
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 high-quality reliable sources; (d) neutral presentation of viewpoints; and (e) stable content.
Style compliance: it follows the entire Manual 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.

Similarities

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 comply with only five style guidelines; featured articles must comply with all style standards.
A featured article must have consistently formatted inline citations; a good article need only have enough information about the source so that the reviewer can figure out which source is being cited, and formatting is optional.
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.
A good article must be verifiable against reliable sources; a featured article must cite high-quality sources. The inline citation requirements are stricter with featured articles.
Good articles are generally not required to be as well-illustrated by media.