Language constructs are used and behave almost similar to built-in functions .
The real difference lies in how PHP engine interprets a language construct and a built-in function. language constructs are relatively faster over built-in functions since they are bound to the language.Language Constructs Don’t Need Parenthesis .Language constructs are faster than built in functions

Below given are the examples

echo
die
if
print
unset
isset
empty
include
require