Difference between state of matter and phase
A phase is a region of space where all physical and chemical properties are uniform. This means that for example the density, the chemical composition and the temperature is equal everywhere in the region. This will also mean that the state of matter (solid, liquid, gas, etc.) is equal everywhere.

A state of matter is a form that matter can take. Examples are solid, liquid, gas, plasma. There are some others that appear under extreme conditions. 

For example, nitrogen and water at 50K are both solid, so they have the same state of matter. However the chemical composition is not the same and hence they don't have the same phase.