It's mysql or mysqld?

"d" stands for "daemon" and this is the server service. mysql is the command-line client program. This is for Windows and Linux, didn't test for other OSes

Don't worry about service names - they can be customized... by default, mysql takes MySQL as service names on windows machines.

If you want to change the service on either machine, just uninstall the service..

/path/to/mysql/bin/mysqld --remove mysql 

Now, you can rename it... say Neelima

/path/to/mysql/bin/mysqld --install Neelima 

Now you will see a service name called Neelima for MySQL server...

Back to the difference between mysql & mysqld (forget service names here) --

mysql -- a command-line client for executing SQL statements interactively or in batch mode.

mysqld -- the MySQL server.

Mysqld = Mysql + D

D stands for Daemon

Pronounced DEE-mun or DAY-mun. Daemon is a process that runs in the background and performs a specified operation at predefined times or in response to certain events.

Hope it clears MySqld

mysql -- A command-line client for executing SQL statements Like Terminal in ubuntu