认证是验证实体身份的过程。例如

Webserver每次都要求用户输入登录名/密码，以验证创建该帐户的用户是否是现在正在访问该帐户的用户。

授权是允许每个实体获得所需数量的服务/资源的过程。例如

On blogging site (eg. medium.com) users can create an account and write a post and publish. And users can read all posts published by others as well. Here the blogging server first authenticates the user with the user login credentials (login/password) and then it authorizes to read all others post and write/modify the post only created by the user. Here authorization is used by the server to limit which all post each user can modify. Users can create a free google account by which google server provides free services like mail, calendar, chat, drives etc. But the storage provided for all these services to free users are 15GB (as of now). User can pay a monthly or annual fee to google server to increase the storage space. Here google server authorizes every authenticated user to limit the amount of resource usage.

在当今的互联网中，授权被广泛用于对客户端施加访问限制。

更详细的答案请参考:https://www.okta.com/identity-101/authentication-vs-authorization/

正如身份验证vs授权所言:

Authentication is the mechanism whereby systems may securely identify their users. Authentication systems provide an answers to the questions: Who is the user? Is the user really who he/she represents himself to be? Authorization, by contrast, is the mechanism by which a system determines what level of access a particular authenticated user should have to secured resources controlled by the system. For example, a database management system might be designed so as to provide certain specified individuals with the ability to retrieve information from a database but not the ability to change data stored in the datbase, while giving other individuals the ability to change data. Authorization systems provide answers to the questions: Is user X authorized to access resource R? Is user X authorized to perform operation P? Is user X authorized to perform operation P on resource R?

参见:

Wikipedia上的身份验证与授权

在用户环境中:

身份验证=验证用户的身份(从技术上讲，你可以验证很多不同的东西，比如密码、税务信息、社会安全信息、驾照、指纹或其他生物识别信息……但通常用户名/密码就足够了)

授权=允许用户做某事(你可以设置角色['管理员'，'卖家'，'买家'…权限['访问控制中心'，'删除产品'…并将这些角色赋予用户，然后验证用户有一个允许他执行操作的角色)

权限与CRUD操作有直接关系，因此如果构建一个UI，您可以将对象列为行，并在任意给定角色的对象权限的创建、读取、更新和删除的4列中设置复选框。

就像在我上面的例子中，“访问控制中心”是对控制中心对象的完整的创建、读取、更新和删除访问，而“删除产品”是对产品对象的删除访问。

注意:HTTP授权头用于访问资源的权限，但实际上用于所有资源访问的身份验证。

在我的头脑中和代码中更容易想到验证和权限，因为这两个词

听起来不一样 不要有相同的缩写 授权的实际实现通常涉及角色和权限的实现

身份验证是验证，授权是检查权限。Auth可以是任何一种意思，但更常用的是“用户认证”，即。“用户身份验证”。很多时候没有显式的授权实现(角色和权限)，只是使用身份验证来提供执行每个可用操作的授权。这就是Auth。

认证是识别有效用户的过程。

授权是验证用户访问级别的过程。

应用程序示例 用户A、用户B均为库存应用的认证用户。 两个用户都可以进入股票，但B对发行项目有更多的授权权力。

补充@Kerrek的答案;

身份验证为通用形式(所有员工都可以登录机器)

授权是专用形式(但管理员只能在机器上安装/卸载应用程序)