ITIL is transitioning from ITIL 4 to ITIL (Version 5).
Your ITIL journey can begin in either program, and no rework, retake, or bridge class is required to progress to higher level ITIL Version 5 programs from ITIL 4 Foundations.
Persons looking for a core grounding in the ITIL Practices (e.g. incident management, change enablement, service desk, etc.) will prefer to start with ITIL 4 Foundations; half of the course provides a core grounding in 15 ITIL practices.
ITIL (Version 5) Foundation focuses more on the Product and Service Lifecycle Value Chain. Coverage includes Discovery, Design, Acquire, Build, Transition, Operate, Deliver, and Support activities.
Practice coverage is limited to alignment with these core activities. Candidates looking for deeper coverage of the ITIL 5 practices should consider follow on courses such as Monitor, Support, and Fulfill (core operations) or Plan, Implement, and Control (change).