Wikipedia:The difference between policies, guidelines and essays

The difference between policies, guidelines, and essays on Wikipedia is obscure. There is no bright line between what the community chooses to call a "policy" or a "guideline" or an "essay" or an "information page".

This explanatory essay itself is a supplemental page, which is an even more ambiguous group. Essays, supplemental, help (how-to), information and template documentation pages generally have a limited status during deliberations as they have not been thoroughly vetted by the community through the policy and guideline proposal process. However, some essays and supplemental pages are widely accepted as part of the Wikipedia gestalt, and have a significant degree of influence during discussions.

How-to and information pages typically provide technical and factual information and are not often referenced during deliberations, but rather used for directing editors to pages about Wikipedia's processes and practices.

Misconceptions
Various theories have been put forward as to what these differences are. Here are the most common misconceptions:

Breaking policies will always get you blocked

 * It's true that violating (some) behavioral policies like the three-revert rule can get you blocked, but so can violating (some) guidelines, and even (some) essays. For example, the essay Single-purpose account and Here to build an encyclopedia are often cited in discussions about blocking and permanently banning editors.
 * On the other hand, violating other kinds of policies, such as Verifiability, is done constantly, by thousands of editors each week, without anyone getting blocked because of such violations.

Policies are succinct

 * Some editors wish this were true, but it isn't. Some policies, such as What Wikipedia is not, which weighs in at 60 kB, are more than ten times the length of some guidelines and essays.

Policies tell you what you must always do, and other pages just make optional suggestions

 * There are a remarkable number of exceptions and limitations embedded within Wikipedia's policies, and all policies need to be applied with common sense. Many guidelines, on the other hand, tell editors exactly what to do in a given situation.  The External links guideline, for example, does not permit any exceptions to its prohibition on linking to known copyright violations.  Furthermore, Ignore all rules is a major policy:  We would not have a policy telling us that all policies and guidelines may be ignored (for sufficiently good reasons) if no exceptions could exist to policies.

Policies are prescriptive, and other pages are descriptive

 * This is usually combined with the erroneous belief that "prescriptive" means that the page uses imperative verbs, like "Do not ____", and "descriptive" means that the page uses the word "should" and various weasel words.
 * In fact, the primary difference between being prescriptive and descriptive is whether the page is telling people what to do, or whether it is describing what people already do.
 * The major content policies, in particular, arose out of the community's actual practices, and thus are correctly considered descriptive pages, even when they describe the community's long-established and widely supported practices in unflinching terms. Any page may use—and many should use—clear, firm, and direct language when describing a firmly established practice.

Policies are supported by a higher degree of consensus than guidelines

 * There is some truth in this: As a general rule policy pages tend to be watched by more editors, and changes to them scrutinized more closely. But there is no guarantee, in any concrete situation, that a given page marked as policy better reflects the will of the community than a given page marked as a guideline. Indeed, sometimes the watching editors' resistance to changes in the text of policy pages can actually prevent those pages from evolving to reflect changed consensus in the wider community. (And some pages are policy only because they were marked as such a long time ago, when standards were different; some of them date back before Wikipedia distinguished between policies and guidelines.)
 * At the other end of the spectrum, some of the most widely supported advice pages, like WP:Bold, revert, discuss and Snowball clause are supplement pages, and Use common sense is an essay.

A page is a policy because everyone reads it

 * Some policies are rarely viewed or commented on. Some essays, supplemental and information pages are viewed thousands of times each week and are widely supported, such as Arguments to avoid in deletion discussions and BOLD, revert, discuss cycle. Nevertheless, how much a page is viewed or its number of incoming links does not always determine the page's status within the community.

Policy pages outrank guidelines, which in turn outrank essays

 * This is actually true in some cases, but not always. First of all, what's written on any given advice page at any given moment may not accurately reflect the community's view—and it's the community's actual view that is the real policy, not the words on a page that says "policy" at the top.
 * More importantly, editors need to follow the most relevant advice. A broadly worded policy page, intended to provide only the most general outline of the goals, is not necessarily a better source of advice than a guideline that directly and explicitly addresses the specific issue at hand.  For example, even though Verifiability technically allows low-quality, self-published blog postings as sources (under some circumstances), one would not wish to prefer such sources over the high-quality, independent sources published by third parties that are recommended by the Identifying reliable sources guideline.