@bobdunn-trainer: You’re using the wrong terminology and confusing things.
Add-ons and Subdomains are completely different animals.
At Bluehost – and many other hosts – an “Add-on domain” is not a “subdomain.”
An Add-on domain – set up with the Cpanel option “Add-on Domains” – provides a full and different domain other than the main account domain, i.e. my-add-on-domain.com and mymydomain.com (the main accont domain)
A subdomain is just that: mysubdomain.mymiandomain.com. Subdomains must be setup with the Cpanel option for a “Subdomain.”
And, Add-on domains at Bluehost are not called subfolders, even though the new domain will appear as a folder in public_html with the name of the domain.