A look further into the difference between a form and the material objects in the world is the properties that characterize the form need to be taken into consideration.
The first property of form is that it is transcendent; in a way that a form cannot be physically perceived; it has no existence in space and or time where as a ball for example (material object) on the contrary can be physically perceived and does have a physical existence in space and in time. A form though does exist in a different way but not in an place or time and this is an important note because it explains why they are unchanging. The form of roundness for example is always the same in all places and in all times where it can be exemplified. A from can be exemplified in more than one place at the same time and not be exemplified in a physical manner for its existence. Be it the case that all objects that have the property of roundness disappears the property of roundness itself will not disappear and will always
exist.
The second property that characterizes the form that need to be taken into consideration is the property of purity; forms are pure in a sense that that the properties are pure and are separate of all other properties. On the other hand a ball for example is made up of individual properties like the color (redness), weight and roundness which collectively make up this ball. The form of roundness is just a single property pure in a sense that it is in existence by itself not in space and not in time and without; the form of roundness in this case can be seen to be transcendent and pure where as on the other hand material world objects are seen as complex collections of properties that can be physically seen and perceived in space and in time.