Social network = connected nodes, each interaction is typically free (content)
Market network = connected nodes, each interaction typically involves payment
Marketplace = a forum for buyers and sellers (can be 2 sided, 3 sided etc..)
Market network = an N-sided marketplace (thus it looks like a network)
Seems like (someone correct me if I'm wrong) the "network" part is about how users can have profiles and use these profiles as their portfolio. So a network of people/ providers.
Also, the SaaS part seems just thrown in there, like ketchup on French food.
I'm not necessarily sold on their premise, but the network part is about types of fields where professionals are not interchangeable, so relationships, vetting, recommendations, professional cooperation are important dynamics.
The question then becomes: if presenting on this to an investor, how would another investor defend the difference as being more than just a repackaged term?