Audit program versus audit plan

Answer:
Consider the following image:

The audit program lists all the audits that an organization intend to execute within a certain time frame.
Normally, an audit program includes scope for each audit, month or week when the audit should be done, and audit team composition and who is the lead auditor. The audit program is made by the audit manager or management system manager, the audit program is better to be approved by top management to give authority to internal auditors.

For each audit included in the audit program, the lead auditor is responsible for preparing and approving an audit plan that is sent to auditees, sometime before an audit, to communicate audit date, audit objective, auditors, and audit schedule. An audit plan allows auditees and auditors to agree on date and schedule.

The following material will provide you information with more information about the audit program and audit plan:
- ISO 14001 – Creating an ISO 14001 internal audit plan - https://advisera.com/14001academy/blog/2017/01/16/creating-an-iso-14001-internal-audit-plan/
- ISO 14001:2015 Internal Auditor Course - https://advisera.com/training/iso-14001-internal-auditor-course/
- book - THE ISO 14001:2015 COMPANION – A A Straightforward Guide to Implementing an EMS in a Small Business - https://advisera.com/books/the-iso-14001-2015-companion/