It's really, really tricky to figure this out. Firstly, although I was obviously being flip, it does vary hugely. There are those who are just in it for the cheque and there are those that are keen to be involved, and there are lots of shades of grey in between.
In general, Ally's distinction is probably right, but it is only a generalisation.
And it is very, very hard for outsiders to figure out exactly how much the signature name does, because everything about the business is set up to convince people that he or she does everything.
Most (emphasise most, but not all) signature projects have a commercial underpinning, whether that is a tourist resort or a real estate development. Mostly, again, those projects are more complicated, from an engineering point of view than the kind of pure golf course development we like to focus on on here. Mr Signature is not generally sitting at a CAD screen doing grading plans, or working on stormwater management, or figuring out how to deal with environmental restrictions that prevent work being done on part of a site.
But he might be explaining to his colleagues in the project where he thinks a bunker should go, or what a green should look like. Or then again, he might not!