Good questions! Each of the teams has selected the boat and crew that they feel will be best for the job.
Bear Grylls' team is a crew of four plus a cameraman (Charlie Laing). Carol McFadden is a passenger and is only on board for the first leg from Halifax to Battle Harbour.
Alan Priddy's team is also a crew of four, except Clive has double duties as journalist and cameraman.
Alan Priddy chose to have a moderate size engine (240hp is not a lot for a boat this size) to maximise fuel economy.
Bear Grylls chose to have a jet drive to minimise the chances of damage from floating objects. As jet drives are less efficient than conventional drives a bigger engine is required.
Their boat is bigger than Jolly Sailor and may well be heavier despite not having a cabin as such, needing more power to push it along. I doubt that the Bear Grylls boat (which doesn't appear to have a name as far as I can see!) is any faster than Jolly Sailor. It will certainly require more fuel.
The choice of route is really dictated by refuelling requirements. A boat with a smaller range will need to make more stops.
The simplest tests are "Did they get across the Atlantic?" and "How long did it take?".
The governing body for world powerboat records is the UIM (Union Internationale Motonautique). The UIM only recognises one trans-Atlantic record, which starts at the Ambrose Light off New York and finishes at Lizard Point in Cornwall. As such, neither team stands to set an official world record.
Assuming that they are both successful, each team will doubtless make whatever claims they feel sound best! Fastest, fastest open boat, fastest under 11 metres, youngest, oldest, fewest stops, most times across the Atlantic.
Funny things records . . .