The $poet Shakespeare said, "Tis better to have loved and lost than never loved at all."
The \$poet Shakespeare has also said "To be or not to be, that is the question."
The first echo/sentence uses an escape character, while the second sentence does not.
An escape character is used when you want to insert a special character in a string that either the program or web would otherwise not be able to read/interpret correctly.
For example, the first echo uses an escape character before the inner double quotations in order to let the system know that the second set of double quotes are meant to be read as regular quotes (within that echo).
Meanwhile, if you dont use an escape sequence, It could lead to the echo/sentence being read/interpreted wrong and cause an error (specifically, a php parse error) that could break the page.