An administrative area is a designated space for subject matter experts to manage content and interact within their lines of business. Company administrators assign area administrators to administrative areas. Area administrators have a subset of company administrator capabilities to perform area-related tasks. The company area is created by default and it is the top level of the internal structure of the site. Information on the company level is visible to all users in the company. There can only be one company level. If you want to add multiple subsidiaries or business areas, you can create different administrative areas for them. Reference:
Administrative Areas
Area & Workspace Configuration

Home pages are the landing pages that users see when they access SAP Build Work Zone. They can display information that is relevant to the company, an area, or a workspace. There are some aspects that need to be considered when working with home pages, such as:
Home pages have a dedicated content area that can be customized using the page builder. The content area is where you can add rows, columns, widgets, cards, and other elements to create a layout for your home page. The content area is different from the feed area, which shows the latest updates and notifications from the company, area, or workspace1.
The home page editor has different layout options compared to workspaces. The home page editor allows you to create a persistent navigation bar with links to other pages or external URLs. You can also add a header image and a title to your home page. The workspace editor does not have these options, but it allows you to add tabs to organize your content into different pages2.
Some aspects that are not true about home pages are:
External home pages can only be configured in the external user Company Admin Area. This is not true, because external home pages can also be configured in the external user Area Admin Area. External home pages are the home pages that are shown to external users, who are users that do not belong to your company but have access to some of your content. You can create external home pages for the company level and for each area level. To do so, you need to switch to the external user Company Admin Area or the external user Area Admin Area, which are separate from the internal user admin areas3.
Company area home pages are always shown to all users. This is not true, because company area home pages are only shown to the users who belong to that specific area. Company area home pages are the home pages that are designed for a specific area or department within the company. They display information that is relevant to that area and also include the area feed. Content is shared by everyone in the specific area. To create a company area home page, you need to be an administrator that is assigned to that area1.
Reference:
Home Pages
Adding Content to Workpages
External Users

A subscription of SAP Build Work Zone is an application that allows users to access the solution and its features, such as creating and joining workspaces, accessing integrated tools and applications, and personalizing their sites. A service instance of SAP Build Work Zone is a space in SAP BTP where the solution runs and where content packages and UI integration cards can be deployed using APIs. Both the subscription and the service instance require the activation of SAP Cloud Identity Services (IPS) as a prerequisite, but only the subscription requires a post-booster activation of IPS to enable user authentication and authorization. The post-booster activation of IPS is a step that must be performed after creating a subscription of SAP Build Work Zone in the SAP BTP cockpit. It involves configuring the IPS settings, such as the identity provider, the trust configuration, and the role collection mapping. The service instance does not require this step, as it inherits the IPS settings from the subscription. Reference:
Create a Subscription for SAP Build Work Zone
Create a Space and a Service Instance
Deploy Content Packages Using APIs
Deploy UI Integration Cards Using APIs

To implement SAP Build Work Zone, advanced edition in a multi-tier landscape, you need to create subscriptions in separate SAP BTP subaccounts. This is because SAP Build Work Zone, advanced edition is a subscription-based service that requires a dedicated subaccount for each tenant. You cannot create multiple subscriptions or service instances in the same subaccount, nor can you create multiple sites within a single subscription. Each subscription represents a separate site with its own content, configuration, and users. By creating subscriptions in separate subaccounts, you can align your SAP Build Work Zone landscape with your core business system landscape and enable content transport across different tiers. Reference:
Explaining the Planning Landscape for SAP Build Work Zone
Getting Started With SAP Build Work Zone

SAP Build Work Zone is a service on SAP Business Technology Platform (SAP BTP) that runs on the Cloud Foundry environment. It is not available on the NEO environment, nor as a standalone on-premise solution. SAP SuccessFactors Work Zone is a product that provides HR-specific content and integration with SAP SuccessFactors HXM Suite on the SAP Build Work Zone, advanced edition solution. It is not a separate module of SAP SuccessFactors, but rather a complementary offering that enhances the user experience and productivity of HR processes. Reference: What you should know about SAP Build Work Zone, standard and advanced edition - formerly known as SAP Launchpad Service and SAP Work Zone | SAP Blogs, SAP Build Work Zone, advanced edition | SAP Help Portal, SAP SuccessFactors Work Zone | SAP Help Portal