The semantic feature comparison model is used "to derive predictions about categorization times in a situation where a subject must rapidly decide whether a test item is a member of a particular target category".
[1] In this semantic model, there is an assumption that certain occurrences are categorized using its features or attributes of the two subjects that represent the part and the group.
Based on the previous observations, the proponents were able to come up with the semantic feature comparison model.
The second concept explains how memory can alter the way we perceive representations of something, by determining the sequence in which the information is processed based on previous experiences.
Defining features refer to the characteristics that are essential elements of the category, the non-negotiable, so to speak.