* Gray horses are born with a darker coat color (often black, bay, or chestnut) but their coat gradually turns lighter with age. This process involves the production of more white hairs, eventually leading to a predominantly white coat. So, a gray horse starts dark and ends white.
* White horses are born with a white coat and stay that way throughout their lives. They are considered a true color, meaning they do not have a base color that changes.
Therefore, gray horses are the closest thing to a "white and gray" horse because they go through a phase where they have both white and gray hairs.
It's important to note that roan horses can also have a mix of white and another color, but they have a different pattern than grays. Roans have evenly mixed white hairs throughout their coat, not just a gradual lightening with age.