See below the use of each feature:
They basically serve to set up lists based on all the lodgings in your portfolio, regardless of their location.
The main purpose is the internal organization of your Stays.net and also on the website, during user navigation on the page.
There is no relation between availability or rates between group members.
The vertical rate groups are used for lodgings that are at the same address and have the same nature of services, according to hotel room categories.
As for the horizontal rate groups, they are used for lodgings located at different addresses, but which have the same pricing, which main use is to speed up the process of registering the daily rate.
Both groups are related to sales channels and, in some cases, there are also implications in the lodging availability.