Welcome to both - @DanielP and your wife, and @aliceyaxley. It might be I’ve welcomed you here once already Alice, but I’d forgotten so warm welcome again.
Daniel, as Alice says, there are two kinds of material - Old course which is called Courses and contains Course 1, Course 2, Course 3 and two Vocab courses of 10 lessons each to Course 1 and 2 - and new material called Levels and consists of Level 1, Level 2 and newly beginning to be published Level 3. Both, Levels and Courses have 2 versions of which one is Southern and one is Northern. Northern has @aran and @CatrinLliarJones as presenters in both, old and new material and Southern has @Iestyn and @anon86454181 as presenters. Both - Southern and Northern Levels and Courses are twinned but varies of words/structures of Southern or Northern dialect. Yours is only to choose which one version - South or North - would suit more to you (maybe on the basis where you live, where you want to travel too etc).
Music at the old course is instrumental intro/outro music and in new Levels it is performed by famous Welsh singer/group who gladly gave the permition to use it in the material.
As Alice says, you might found yourself picking one version the first time you’ve made the lessons and the other version when you wanted to continue.
Nowdays Levels (new material) is more recomemended then old as new one includes listening practices (from Challenge 10 on a double speed with the purpose) and the aproach is such that you can progress with learning faster than with old material. But, here again, you can try both and see which suits you more.
If you just can’t quite decide which material or which version of it would be best to choose you can visit the topic Course 1 VS Level ! and North VS South and read what other members of the forum were choosing and why or what best suits them. The deceision might be a bit easier for you then too.
I hope it helps a bit to disclose a mistery of unknown. 
Otherwise if there are some other questions you can freely ask and there will be surely members who will respond quickly or you can alternatively cruise through the forum and explore things of your interest.
Happy learning.
Hwyl!
Tatjana