As a Salesforce end-user, I use my org's Salesforce
Salesforce apps with console navigation let you open multiple records at a time, and related records open in subtabs under the original record.
Salesforce apps with standard navigation let you open a single record at a time.
Salesforce sandboxes are copies of your Production environment (where users login and work with live data). A sandbox contains all the configurations, customizations, apps, and code (collectively known as metadata) that exist in your Production environment at the point the sandbox was created or refreshed.