Most people do not know the difference between the two things, a gravestone is simply a stone slab laid over a grave, and it consists of the deceased name and dates.
On the other hand, a headstone is also known as a cornerstone; it’s way much different from a gravestone because, as for this one, it is just meant to sit at the cneorner of a building.
A headstone also consists of names but those of builders and can also have starting and ending days of construction; it can also some interesting information about that building.
The two can be confusing, but they are totally different but keep in mind that a headstone has information about the building while a gravestone has details of whoever was buried at a certain grave.
It’s always important to know the difference so that you don’t use the wrong term for the wrong purpose. Another thing you should know is that a gravestone sometimes has certain symbols which headstones don’t have.