These two applications automatically create activation targets when they are connected to Data Cloud. You can use these targets to activate segments or calculated insights to these applications. References:
https://help.salesforce.com/s/articleView?id=sf.c360_a_data_cloud_activation.htm&type=5

The sales order subject area defines the revenue or quantity for an opportunity by product family. It also includes information about the opportunity stage, close date, and owner.References:https://help.salesforce.com/s/articleView?id=sf.c360_a_data_cloud_sales_order.htm&type=5

These two options are recommended ways to bring transactional data from a data warehouse into Data Cloud via a SFTP site. You can use the Cloud Storage Connector to ingest files from Google Cloud Storage or Amazon S3 buckets into Data Cloud. References:
https://help.salesforce.com/s/articleView?id=sf.c360_a_data_cloud_google_cloud_storage.htm&type=5
https://help.salesforce.com/s/articleView?id=sf.c360_a_data_cloud_amazon_s3.htm&type=5

These two options are recommended ways to bring transactional data from a data warehouse into Data Cloud via a SFTP site. You can use the Cloud Storage Connector to ingest files from Google Cloud Storage or Amazon S3 buckets into Data Cloud.
References:https://help.salesforce.com/s/articleView?id=sf.c360_a_data_cloud_google_cloud_storage.htm&type

Explanation
The party subject area should be used for any organization, individual, or member in the Customer 360 data model. It includes information such as name, address, email, phone, and loyalty membership.
References:https://help.salesforce.com/s/articleView?id=sf.c360_a_data_cloud_party.htm&type=5