What is the difference between APX 4500 and 6500?

I'm curious to understand the key differences between the APX 4500 and the APX 6500. Could you elaborate on their performance capabilities, intended use cases, and any notable technological advancements that set them apart from each other? Are there any specific features or benefits that one model offers over the other, and how do they compare in terms of scalability, security, and cost-effectiveness? I'm interested in a comprehensive breakdown that helps me decide which one might be the better fit for my needs.