If Brit’s Call yards gardens than what is a garden called?

They call them gardens, but with modifiers: flower gardens, vegetable gardens, rock gardens, herb gardens, or such.

I'd say a yard (in the UK) is loosely classed as a working or storage area, a functional place or vehicle standing, foot path etc., while gardens are decorative or for play & relaxation.

There is a difference between a back yard and a back garden in a house, for example.

A yard may have some form of paved surface or be packed earth, grass etc., but if grass it would be incidental rather than being considered a lawn.

Think of such as a "Farmyard" - vehicle paths, storage, barns etc. whether it's a formally paved surface or just rough ground with grass and weeds. Very different to a garden.

A garden is called a garden. There's no need for another word. If you need to hone in on individual features in that garden there are words for that. Yard has another meaning in British. It is a paved, workaday area, such as a stable yard, a farmyard, or a scrapyard (that would be a junkyard in American). It's weird for a Brit to see grassy areas called yards. Funnily enough both words come from the same root word meaning an enclosed/ fenced off area. Words are like water in a stream diverging and converging again.