Splunk 7.x Fundamentals Part 2 (IOD) vs. Splunk 7.3 Fundamentals Part 2

What is the difference between **Splunk 7.x Fundamentals Part 2 (IOD)** and **Splunk 7.3 Fundamentals Part 2**? I want to pursue the Splunk Enterprise Certified Admin Certification . . . but not sure which course is next in the sequence. Thank you for your help.