Philosophy or approach to their training programs.
Experience. Background in what they’ve worked with client wise. Pushing people to failure or exhaustion.
Hiring a trainer with more experience may mean they’re better at stand alone procedures and wont need to be brought into a programs for sales, they may have their own magic. But they may also have a harder time adapting. Visa Versa a trainer with less experience may need help with sales, but they may be able to learn programs in place.