Burn an iMovie onto dvd to play in dvd player

I want to create a dvd of an iMovie I made so my mum can play it in her DVD player.

its just over an hour long but won’t fit on a dvd r 4.7g.

how can I fit it on the disc or

can I use a double layer 8.5g dvd+r.

what is the difference between a dvd-r or a dvd+r?

thankyou