The Extended Diploma is the same destination as the 120-credit diploma above it, reached from a different starting point. A learner with a Level 3 qualification, or two A levels, registers once and works through twelve units: six at Level 4, then six at Level 5. At 2,400 hours of total qualification time and 1,200 guided learning hours it is exactly double the single-level programme, and OTHM labels every unit with its level so there is no ambiguity about which half you are in.
The Level 4 stage is foundational in the literal sense. Academic Writing and Research Skills comes first because everything afterwards is assessed by writing; Business Operations, Communication in Business, Finance and Accounting, Leading and Managing Teams and Operating in a Global Context then cover the functions a Level 5 strategist will later be asked to integrate. The Level 5 stage mirrors the standalone diploma: strategy, human resources, marketing, business law, management accounting and the start-up project.
One caution on the data: OTHM's own published unit list spells the first Level 5 unit "Principals and Concepts of Strategy". This site reproduces titles as the awarding body publishes them and we have reported the spelling; the unit content is identical to the standalone diploma's Principles and Concepts of Strategy.