Difference between Contacts and Targets in a target list

Dear All,

Just started playing with suiteCRM and so far I like what I see.

I’ve got a list of email addresses that I need to send a ‘group email’ too. To do this I was going to create a 'marketing campaign, but part way through I realised that a Target List may be simpler.

So I created a Target List, which was very easy.
When I view the list there are a number of opening sections on the screen, 2 of these have me a little confused. They are
Targets and Contacts.

Can someone please explain the difference between the 2, and how best to use them.