The root and alias instructions in the Nginx configuration are detailed

Both Root and alias can be defined in the location module, which is used to specify the true path of the requested resource, such as:

location/i/{
ROOT/DATA/W3;
}

When requesting http://foofish.net/i/top.gif this address, the real resource in the server is the/data/w3/i/top.gif file, noting that the real path is the value specified by root plus location specified value.

And the alias, like its name, alias specifies a path that is location alias, regardless of how the value of the location is written, the true path of the resource is the path specified by the alias, such as:

location/i/{
alias/data/w3/;
}

When the same request is http://foofish.net/i/top.gif, the resource path that is found on the server is:/data/w3/top.gif

Other differences:

The alias can only function in location, and root can exist in the server, HTTP, and location.
The alias must end with "/", otherwise the file will not be found, and root is optional for "/"