The Wikimedia Foundation (WMF) is the multinational organisation that owns and manages the Wikimedia platforms and the server infrastructure to run them. The organisation is responsible for managing the overall budgets and has funds available for Wikimedia affiliates. It also coordinates the founding of national Wikimedia chapters and other Wikimedia movement affiliates like user groups.
Wikimedia Belgium is recognised as the official Belgian Wikimedia chapter by the Wikimedia Foundation and gets funded by the Wikimedia Foundation through grants. In return Wikimedia Belgium has to publish annual reports (on activities and financials) and has to provide metrics and receipts or invoices as evidence for the costs/reimbursements Wikimedia Belgium has paid for.
Together with the worldwide Wikimedia communities and affiliates the Wikimedia Foundation is part of the global Wikimedia movement.