When ordering for delivery, your customers will select from a list of Store Groups (if more than one exists and the option to automatically select the best Store Group is disabled). And when ordering for collection, end-users will select from a list of Stores.
By grouping Stores into Store Groups, you improve your customers' delivery online ordering experience by not requiring them to select a particular store when ordering. Instead the Flipdish software will automatically select the best Store for the customer based on
whether the customer is within the Store's delivery zone
whether the store is currently open
the proximity of the Store to the customer
When you have multiple Stores under the same brand serving similar menus (think Subway, Domino's etc) then best practice is to group them under a single Store Group.
Reasons to place stores in seperate Store Groups include
to allow customers to select which Store will fulfil their delivery order
if your Stores have different currencies (eg. CAD and USD)