different between multisite and multivendor

Hi,

HikaMarket Multivendor is a Joomla extension which main purpose is to add multivendor capabilities to HikaShop. With it, you can sell, on the same Joomla website, products from different vendors. You can have a fee / commission mechanism where you get a percentage of each sale and the vendors get the rest. Vendors can be allowed to manage their products / orders on the frontend, or not.
So basically, its purpose is to turn a website, or part of it, into a website like Amazon, or our marketplace:
www.hikashop.com/marketplace.html

HikaShop Multi-sites is an edition of HikaShop itself, like HikaShop Starter, Essential or Business.
HikaShop Starter is the most basic one, and the Essential and Business editions add extra functions to it.
HikaShop Multi-sites actually has the same capabilities as HikaShop Business. The difference is that a HikaShop Business subscription gives access to automatic updates, our cron task service and user support for one website, while HikaShop Multi-sites gives access to these services for as many websites as you want.
This is useful if you're a web agency and you build several websites for different clients and you need to provide a HikaShop Business subscription for each one of them. Having a Multi-sites subscription will save you money as you don't have to purchase one HikaShop Business for each website anymore.
So, this won't help you have different domain names for different vendors of a unique website.

If you need to have several websites with different domain names, I would recommend having different Joomla installations, as Mightysites suggest on their website:

MightySites will NOT help you to run hundreds and thousands of sites using a single Joomla installation, please don't contact us with such requests.

MightySites will NOT help you to run multiple independent websites using a single Joomla installation, please use a usual separate Joomla installation for each site in this case.

Now, it is not impossible to configure a Joomla website to serve different domain names, with different templates / menu items / products on each one. This can be done with a carefully configured web server and Joomla.
Here is a thread on the github of Joomla where people talked about this :
github.com/joomla/joomla-cms/discussions/37846