Difference between WordPress Plugins and Widgets

Plugins:
Plugins « WordPress Codex
Managing Plugins « WordPress Codex

Widgets:
WordPress Widgets « WordPress Codex

"Plugins are functions that do something to your website. They could serve a back-end purpose and never be visible to you or the public. In the other hand, a widget usually is the representation of a plugin in the form of an object that can be placed somewhere on your website via the widgets interface under the appearance menu.

Widgets are always plugins, but plugins don't always have widgets."


Wordpress Widgets vs Plugins, what's the difference? - Oscar Gonzalez

WP Plugins can be a widget or just additional code, it can be visible in the front-end or just in the back process of WP. Widgets are elements that you see in the front-end of a WP site, it can be in the sidebar or footer or can be anywhere in the website.

Plugins are little bundles of code that add extra functionality to your website. They are extensions or apps that need to be installed. They usually serve an administrative purpose and are only visible in the admin section of the website.
Widgets are drag-and-drop blocks of content that are visible to everyone on your website. When you want to add something to your sidebar or footer, you add a widget.

Widgets can be plugins.
But plugins are not widgets.

And you can make a widget that is NOT a plugin.

Plugins are the additional functionality that can integrate over wp theme, externally.

Widgets provides built in space to add functionality in wp theme.

Hope this will help you !!

Widgets are blocks of content that are visible to everyone on your website. When you want to add something to your sidebar or footer, you add a widget.
Plugins are little code that add extra functionality.we need to installed diffrent plugins. They are only visible in the admin section of the website.

Plugins are additional functionality that you can add to your wp website, like contact forms, registration forms, payment gateways etc. they are third party software.

widgets are also some sort of plugins, providing some ways on how to arrange your side bar contents like calendar, search box, archives.

wordpress plugins and widgets contain many differences they are;

WordPress Plugins

Plugins are little bundles of code that add extra functionality to your website. They are extensions or apps that need to be installed. They usually serve an administrative purpose and are only visible in the admin section of the website.

For example, WordPress does not have a backup feature. But you can install a plugin that adds that functionality, allow you to automatically make backups of your website. You can see the plugin from your WordPress Dashboard, but it’s not visible to normal visitors on your website.

Widgets are drag-and-drop content areas that can be added to a WordPress site when its plugin is installed and activated. WordPress has quite a few defaults that come with the initial installation, but for added functionality, plugins can be installed to add more widgets to the dashboard. Depending on the theme you are using, you can use widgets in specific widget-ready areas of your site, typically in the sidebar, though some themes will add these widget-ready areas to the header and footer as well.

PlugIns are extensions that must be installed on the server and activated in order to be used on the website. The purpose of plugins varies greatly depending on what it is for.


Some will work in the background, with no need for additional options or settings, while others will add a new menu to the WordPress dashboard to allow you the flexibility of customizing the plugin settings to suit your needs. And still others will add widget functionality to the site, which leads us to...


Widgets are drag-and-drop content areas that can be added to a WordPress site when its plugin is installed and activated. WordPress has quite a few defaults that come with the initial installation, but for added functionality, plugins can be installed to add more widgets to the dashboard. Depending on the theme you are using, you can use widgets in specific widget-ready areas of your site, typically in the sidebar, though some themes will add these widget-ready areas to the header and footer as well.

Plugin development needs programming (php)

Plugin are a third party add-on which can be added to your website for extra functionality that you need.
Widgets provide a way to arrange your sidebar content without having to make any changes in your actual code.
Plugins can provide widgets to showcase it in front end.

Frankly speaking:

Plugins don't show up their asses. They live hidden from the website visitors ( in the Wordpress admin area and provide functionality to your website. That functionality can be visible to the website visitors or it can be invisible).

Widgets essentially show up their asses. They are the containers for holding stuff shown to the website visitors.


.

This article can help you. Check it out.
What is the difference between wordpress plugin and widget? - Stack Overflow

PLugins are the addons you need to install and activate in your Wordpress dashboard to add more funcstions like widgets, popups, seo, gallery etc.


Widgets are the available layouts in your sites that you can drag and drop in your dashboard.

Widgets are drag-and-drop areas that will add specific functionality or features to the WordPress theme.

Plugins are extensions when installed on the server or on the website will add extended functionalities to the WordPress theme.