What is the difference between the states of matter and the phases of matter? Should solid, liquid and gases be called states of matter or phases? How many states and phases are there? Different sources quote different things. Please help
States are more the gas/liquid/solid thing, describing the qualitative behavior of some matter.
Phases describe a collection of matter (often a region) as opposed to that collection's state. This can be confusing because we often refer to phases by their state for convenience.
For example, multiphasic liquid systems have several phases but only 1 state (liquid). A common example is oil and water when the two don't mix; then, there's an "oil phase" and an "aqueous phase".
This might be confusing since some simple examples have one phase per state. For example, when we talk about water boiling, there's a "liquid phase" and "gas phase". Here the regions are the phases and the gas/liquid qualifiers describe the state of matter in them.