The Business Unit Name is displayed in the Business Unit picklist on the Create Transaction user interface and is also displayed in the Audit Trail. The Business Unit API Name is used to specify a Business Unit with the businessUnit Conga Sign parameter and the CSBusinessUnit Composer parameter topic in Composer Parameter Guide. The Business Unit API Name can only contain underscores and alphanumeric characters. It must be unique for the org, begin with a letter, not include spaces, not end with an underscore, and not contain two consecutive underscores.