I know a few people here use WHMCS so maybe someone can help me?

What is the difference between Addons and Configurable Options. Can someone please give me an example of their usage.

Eg SSL, Software Extras, etc..

As far as I'm aware addon's are things you pay for and configurable options are adjustable things for a package.

For example if you we're ordering a dedicated server an addon might be extra IP addresses or backups.

However configurable options would be things like choosing a password, nameservers, control panel requiered, OS required etc..

Thanks for that.

Actually you can charge for configurable options. There is an option to make those changes.

Addons are offered with a product, and these add-ons are optional for clients. Client can easily get it removed and re-order easily.

This link may be helpful:

http://wiki.whmcs.com/Addons_and_Configurable_Options

You could configure addon's such as extra disk space, additional email accounts, extra FTP users and additional MySQL databases