You will get tons of resources about it.
However, check these
- https://www.quora.com/What-is-the-main-difference-between-Symfony-and-Laravel-PHP-Framework
- https://www.toptal.com/php/choosing-between-symfony-and-laravel-frameworks
- https://stackify.com/laravel-vs-symfony-php-framework-comparison/
I am laravel developer, Do i still need to learn symfony? Personally I prefer you learn if you can. It will increase your knowledge to understand and compare.
If someone need symfony developer, can i apply for that job? Again, once you go with quetion 1, yes, in that case you should apply. Even if you don't go with question 1, you need be open minded. My personal suggestion don't strict on any technology. Learn as much as you can.
For laravel developer, what is different and difficult if he want to move to symfony? As of my understanding, laravel grab many components from symfony. Of course, you will see some similarities, along with dissimilarities. Again, as long as you have good knowledge on OOPHP, that's shouldn't be difficular for you.
What are the plus points symfony have while laravel don't? Check above links for that.