The Node.js Child Processes module (child_process) has two functions spawn and exec, using which we can start a child process to execute other programs on the system. Those new to child_process may wonder why there are two functions to do the same thing, and which one they should use. I'll explain the differences between spawn and exec to help you decide when to use what.
The most significant difference between child_process.spawn and child_process.exec is in what they return - spawn returns a stream and exec returns a buffer.
child_process.spawn returns an object with stdout and stderr streams. You can tap on the stdout stream to read data that the child process sends back to Node. stdout being a stream has the "data", "end", and other events that streams have. spawn is best used to when you want the child process to return a large amount of data to Node - image processing, reading binary data etc.
child_process.spawn is "asynchronously async
