Types of errors in php:
1.) Parse Error or Syntax Error,
2.) Fatal Error,
3.) Warning Error,
4.) Notice Error
And of those number 1 and 2 will stop executing your script, while 3 and 4 will not. In other words: in case 1 and 2 your script will not run at all, and in case 3 and 4 you will see an error in your output (depending on how you set your error_reporting()), but you do get output.
Is this a test ? … If it is than just checking php.net as noticed you could have the answer. The only thing that could make any sense related to that question is what is the error – exceptions handling according to error types in PHP, but that seems far away from the original one.