In the US, garden is the area of the yard that grows plants. It is typically a small portion of the yard. The yard is pretty much any open space of the owner's parcel of land not containing the house or other structures. Also commonly used terms are "flower beds" or "plant beds". These are typically for ornamental plants vs food. Most people would consider a garden to primarily be for food plants.
For example, the Great British Bake-off has the tent in the garden. But no red blooded 'murican would consider that expanse of manicured grass as a garden.
For example, the Great British Bake-off has the tent in the garden. But no red blooded 'murican would consider that expanse of manicured grass as a garden.