Load Board Authority vs OO Lease?

Landstar website confuses me a bit in a couple of ways. First, the so-called Owner Operators are lease contracts with many of the paperwork details covered, while the company also has carrier contracts (the real owner operators).

So, am I reading this website right? The lease driver requirements are the usual company background employment stuff--experience, tickets, age, etc., whereas the authority carrier contract is merely by meeting insurance and authority requirements. The carrier is responsible for most things, but it does appear that Landstar has a fuel system for carriers at least.

Second, do the load board OO compete with the lease OO for cargo? That is, are the load board loads leftovers of some sort?

Any clarification of the Landstar system would be appreciated...