7.16 confussion

"To generate a private key, use the following command:

$ openssl x509 -req -days 365 -in server.csr -signkey server.key -out server.crt"

"To generate a self-signed certificate, you should use the following command:

$ openssl x509 -req -days 365 -in server.csr -signkey server.key -out server.crt"

Are they supposed to be the same? And according to Solution 7.5 there are different commands for these tasks. Am I missing something?