echo() and print() are not functions but language constructs in PHP. They are both used to output strings and there are very minor differences between echo and print in PHP.
Speed of echo vs print in PHP
The speed of both echo and print statements in PHP is roughly the same. Using one over the other is not likely to yield any performance improvement in your application. Theoretically, echo is more efficient because it does not return any value.
Function vs Language Construct
Unlike most PHP string functions,
Parameters and syntax of print vs echo
When used with parentheses (like a function call), both print and echo take only 1 argument. For example,
echo("Don't panic!"); print("The answer is 42.");
However, when used without parentheses, echo can take several arguments. For example,
echo "Don't", " ", "panic", "!"; //This is valid. print "The ", "answer ", "is ", "42."; //This is invalid.