How do i update the droplet? Confused with what command to use seeing the answers.

Hello,

I am using Ubuntu 14.04 x64. I have tomcat7, Java, nginx, postgres. Every time i log into my droplet using terminal,i get this : 227 packages can be updated. 126 updates are security updates.

I searched for this question here and got a lot of answers, but i am confused with what command to proceed with. Listed all the questions pointing to the same and their answers :

1. Link 1 gives this as an answer : There most likely will be a restart required for a few of them. Shutdown & snapshot then run this: sudo apt-get update && sudo apt-get -y upgrade && sudo apt-get -y dist-upgrade && sudo reboot Note: That command will automatically say yes to all updates and will restart one it completes updates. If something breaks or you are having issues, restore back to the snapshot.*
2. Link 2 says to use : The most basic way of applying updates would be to use apt-get from the CLI. apt-get update apt-get upgrade Before running apt-get upgrade I would recommend backing up core configuration files though, if you’ve made changes (i.e. nginx.conf, php5-fpm.conf, php.ini etc) as there is potential for them to be overwritten.
3. Link 3 gives this as answer : Updating packages normally does not overwrite config files and even if it did, they are usually coded to update your config file with your settings. But it is a good idea to take a snapshot of your droplet before doing any updates. And to update, you can run the following commands, sudo apt-get update sudo apt-get upgrade This is my question only. Im sorry for writing again. Today i was about to do any update and saw a few more answers regarding it, so got confused.
4. Link 4 gives this as a answer : You can try the following cli to keep your droplet up-to-date, clean and secure: apt-get update && aptitude dist-upgrade -y && apt-get autoremove -y.

My questions are:

1. Are the security updates required command different than the package update required commands?
2. Will the commands override any of the config files?
3. What commands should i use to update both packages and security updates? Should i use :
   • sudo apt-get update && sudo apt-get -y upgrade && sudo apt-get -y dist-upgrade && sudo reboot OR
   • apt-get update
     apt-get upgrade OR

• apt-get update && aptitude dist-upgrade -y && apt-get autoremove -y.

I am sorry since i am a little nervous with this updates thing. But i know thats its important to have those updates.

Thanks in advance, Kavisha.