addon domains vs subdomains

[electra]

What is the difference between an addon domain and a subdomain? In terms of the website URL, aren't they both located directly to the left of the second level domain?

 

[ultimatewebby]

Add on domain is a domain on top of your main domain. sub domain is a domain under your main domain. hahaha. Do I make sense?

 

[herychristan]

In terms of the website URL, aren't they both located directly to the left of the second level domain?