multisite setup & domains – PRO-SITES vs WHMCS

Hi!

I have a project where I will sell users custom websites, with custom post types etc.

and I want them to be able to create their website on the network either as a subdomain

website for free, or with their own domain – payed. I want to enable them to either bring their

own domain, or to buy domain through my interface/website.

I understand I need Domain Mapping plugin and maybe Multi Domain.

I also understand I will need Pro Sites plugin.

But I also see that WHMCS provisioning plugin (and perhabs WHMCS integration plugin) have their use case – particularly in domain selling part of what I plan to do.

So what is the advantage / difference if I use PRO SITES vs WHMCS plugin/plugins,

because I dont want to sell hosting itself, just sites on multisite network.

Or do I need them both?

Thanks in advance!