In C, both printf and puts functions are used for printing a string on the console and are defined in stdio.h header file¹. However, they have some differences in their usage and behavior.

Here are some of the main differences between printf and puts functions in C:

• printf allows us to print formatted strings using format specifiers, such as %d, %s, %f, etc. puts does not support formatting¹.

• printf does not add a new line character automatically at the end of the output. puts automatically adds a new line character¹.

• printf returns the number of characters successfully written to the console and a negative value if an error occurs. puts returns a non-negative value on success and EOF (end-of-file) on failure¹.

• printf can handle multiple strings at one time which helps in concatenating the strings in the output. For example, printf("Hello %s\n", name); prints "Hello" followed by the value of name variable. puts can print a single string at one time¹.

• printf can print data of different data types, such as integers, floats, characters, etc. puts can print only strings¹.

• puts can be preferred for printing a simple string because it is generally less costly (implementation of puts is generally simpler than printf), and if the string has formatting characters like ‘%s‘, then printf would give unexpected results. Also, if the string is a user input, then the use of printf might cause security issues².

• If you do not want the cursor to be moved to the next line after printing a string with puts, you can use the following variation of puts: fputs(str, stdout)¹.