The Von Neumann architecture is a computer design model that uses a single memory space for both instructions and data. This means that the CPU fetches instructions and data from the same memory, which simplifies the design but can lead to bottlenecks when processing speed is critical. In contrast, the Harvard architecture features separate memory spaces for instructions and data. This allows the CPU to access instructions and data simultaneously, improving performance in certain applications. Both architectures have their advantages and are used in different types of computing systems, depending on the specific requirements of the task.