What is the difference between save the date cards & invites? And when...

Save the dates are just a small card or object (some people use magnets) which just tells people to save the date of your wedding, it's an informal way of telling someone about the actual event, these are usually sent 8-12 months in advance.
Invites are the formal invite to the wedding with all the details guests will need, i.e, date, time, venue etc. These are usually sent 4-6 months prior.
I personally am not sending save the dates, as I feel it is an extra expense when I can send the invite a little earlier and save the postage, however you could email people or have a Facebook page for a save the date. Good luck. x

Emma has it exactly. I'm also not sending save the dates ... I sent a text to those I regularly text and the other's a have spoken to. If it is important to them they will make a note ... if not and they then have something else booked it's their loss (and our gain as we won't have to pay for them)

I have the save the dates as well as invites, I'll be sending my save the date cards in December next year (I get married in November 2019) and then I'm sending invites 6 months before the wedding xx