Explain the difference between readFile and...

readFile load the whole file which you had marked to read whereas createReadStream reads the complete file in the parts of the size you have declared.
The client will receive the data faster in the case of createReadStream in contrast with readFile.
In readFile, a file will first completely read by memory and then transfers to a client but in later option, a file will be read by memory in a part which is sent to clients and the process continue until all the parts finish.

Explain the difference between readFile and createReadStream in Node js ?