Node.js is often preferred for projects requiring scalability, event-driven architecture, and non-blocking input/output due to its ability to handle complex calculations and large-scale applications. Python, on the other hand, excels in web development, numerical computations, network programming, and machine learning, thanks to its ease of use and versatility. The choice between Node.js and Python ultimately depends on the specific requirements of a project, with both offering unique advantages and disadvantages that should be weighed against each other.