POP3 is an incoming mail protocol which automatically downloads the incoming emails of your mail account on the device you will be checking that email account from. It is particularly useful if you would like to have all your emails downloaded on your local device. You also have the option to delete them from the server once downloaded.
IMAP is a mail transfer protocol used for checking the incoming emails of your mail account. The protocol is particularly useful if you would like multiple users to access a single mail account due to the fact that the protocol does not download nor delete the emails in the mailbox.
The setup of the email client is quite easy and intuitive still if you are experiencing any difficulties you should check our detailed tutorial on the subject.