We know that under high pressure, graphite can be converted to diamond. At room temperature, both are solids.
So,
A) Is the state same?
B) Is the phase same?
We know that both graphite and diamond are solids are room temperature. So, we can be sure that the state is the same at room temperature.
But we know the physical properties of diamond and graphite are different although the chemical composition remains same. Properties like refractive index, density etc are definitely different. So, we can say that they are in a differentphase.
Note: Here graphite is said to have undergone aphase transition.