First and foremost, the two systems are important crime reporting units and have been useful in availing important crime information both to the public and the law enforcement agencies. Looking at the data from these two important institutions, one is likely to see a variety of similarity and differences that stem from their original purpose, methodology of data collection, different crime calculation methods and the set of crimes reported.
To begin with, the two programs are similar in terms of the subset of crimes they measure which also are given similar definitions. For instance, data from the two programs show that they both cover rape, robbery, assault, burglary and stealing of motor vehicle among others. More so, crimes like rape and robbery are given virtually the same definitions by the two programs although with little variations on the side of rape which is given some analogous descriptions.
On the side of differences, this begins with the two programs original purpose. UCR was fundamentally established to provide data for criminal statistics to be used by law enforcement agencies in their operation and management of crimes within the nation and all its states. NVS on the other hand was conceived to provide data that previously were not available or overlooked by UCR such as crimes to which the victims failed to report to police. Therefore, one is likely to find certain aspects of crime reported in NVS and not in UCR.
The second significant difference in the two data is found in their overall methodology. Looking critically at their data, one is likely to notice that certain aspects of their definitions of crime differ. This difference is much more evidence in their definitions of burglary. The UCR defines this crime by including the motive of the offender which it says is to commit a felony or theft. NVS avoids the motive of the offender and simply puts it as an attempted or entry into a place where one has no legal right to enter. This kind of difference at least from a face value makes it difficult to compare data from the two programs.