JavaScript is a case-sensitive language. This means that the language keywords, variables, function names, and any other identifiers must always be typed with a consistent capitalization of letters.
So the identifiers Time and TIME will convey different meanings in JavaScript.
NOTE − Care should be taken while writing variable and function names in JavaScript.
Example
The following example shows JavaScript is a case-sensitive language:
<!DOCTYPE html> <html> <body> <h3>My favorite subject</h3> <p id="demo"></p> <script> var subject, Subject; subject = "Java"; Subject = "Maths"; document.getElementById("demo").innerHTML = subject; </script> </body> </html>