Node.js offers two ways to read and operate files that are using readFile and CreateStream. readFile() is a completely buffered process that responds only when the entire file is pushed in the buffer and read. It is a memory-intensive process, which gets very slow for larger files.
Whereas in the case of createReadStream is partially buffered, which takes the complete process as an event series. The file is divided into big chunks, which are then processed and sent back as a response one at a time. Once completed, they are then removed from the buffer, making it more efficient for processing larger files.