The term "composite" refers to anything made of distinct, different parts. Composite insulation, therefore, constitutes any insulation composed of layers of distinctly different materials. This type of insulation exists for myriad applications, from composite sound insulation with layers of different sound-dampening materials to composite weather insulation with multiple layers of material used to control the flow of air to and from an interior environment. Composite insulation appears commonly around things like power cables, capacitors and transformers to help contain electricity for safety purposes.
"Non-composite" refers generically to anything not qualifying as composite. Non-composite insulation, therefore, constitutes all insulation made of a single type of material rather than from multiple distinct materials. Composite materials appear commonly in non-composite insulation. For instance, sound insulation often assumes the form of composite wood boards. Though the material itself qualifies as composite, it constitutes the only material in the insulation. Because the insulation contains only one material, it is technically non-composite, despite containing a composite material.
Composite insulation contains numerous layers of material, each layer made from a distinct material. For instance, according to the book “Plaster, Render, Paint and Coatings,” composite weather insulation typically contains a thermal layer, a reinforcing layer and a coating layer. Composite sheet insulation manufactured by Dupree Products, meanwhile, contains layers of reinforced Mylar, vinyl and foam. Non-composite insulation, on the other hand, contains a single material, such as a blanket of fiberglass or rock wool for weather insulation or wood fiberboards for sound insulation.
The composite vs. non-composite distinction does not affect the way in which you use these materials. Types of composite and non-composite insulation exist for identical purposes; the type you end up using depends upon your needs, budget and considerations such as spatial constraints. You can use composite and non-composite materials in tandem to take advantage of the benefits of each. A Texas State University publication recommends installing non-composite insulation as a bottom layer, then applying composite insulation on top of this layer. You can also use non-composite insulation as an in-between layer when using multiple types of composite insulation together.