Hmm. I've heard how complex and nasty the UK train pricing system is, but it's truly horrid….
All of the above tickets are for exactly the same seats on the same trains from Cambridge to Colwyn bay.
And you can't find them using splityourticket.co.uk.
http://www.splityourticket.co.uk/search-results.aspx?from=cambridge&fromid=&to=colwyn+bay&toid=