Components (both parts and subassemblies) have general properties that are stored in their source files. They also have unique occurrence properties that are stored within the assembly in which they are placed. When you need specific properties for an occurrence in an assembly, you can override a component-level property with an occurrence property.
Within an assembly, you can change the properties of an occurrence by right-clicking the component, and then selecting Properties from the context menu. Some values can be changed temporarily (such as whether a component is visible in the graphics window or whether its degrees-of-freedom symbol is visible). Other settings, such as whether the occurrence is adaptive, are likely to remain in effect during several editing sessions.
Properties that are stored at the part level include material and feature-level adaptive status. Properties stored at the occurrence level include visibility, part-level adaptive status (adaptivity within the assembly), and overrides of component appearance.
Making an occurrence adaptive allows the adaptive status of the part to have meaning in the assembly context. You can make an occurrence adaptive, but if the part is fully dimensioned, geometry does not adapt when the part is placed in an assembly. Similarly, if the part has no adaptive features, making the occurrence adaptive does not cause the part to adapt in the assembly.
For example, you can think of adaptive status like a water valve. Inside a house, there are water faucets (and inside the assembly you have adaptivity). If the main water valve that controls water coming into a house is turned off, water does not come out of the faucets, even if they are turned on. In the same way, if the underlying adaptivity at the feature level is turned off, adaptivity is not available in the assembly.