This is getting confused. In this Kingdom we have three countries making up Great Britain and with Ulster we have the United Kingdom of Great Britain and Northern Ireland.
Many folk confuse England , GB and the UK and the same is true of the Kingdom of The Netherlands.
If you think on "The KIngdom of The Netherlands" being the UK, "The Netherlands" equates to Great Britain. The provinces in The Netherlands equate to Scotland, Wales and England. Two of them are North and South Holland.
So, as with England being confused wi Great Britain and GB being confused wi the UK, there is also confusion wi Holland, The Netherlands and the Kingdom of The Netherlands.