"Is there a strict legal difference?"
Yes, definitely.
If you're a banker selling bundled mortgages and say to a ratings agency: 'I'm going to give you some money, and I want you to lie on your credit rating report that you make of my financial product'. This is fraud.
If you get keep getting bad credit ratings from some agencies, but some others give you good ratings - and you start to spend all of your budget on the agencies that give good ratings ... and then the ratings agencies that are losing business realize they are going out of business, and those agencies start to 'loosen criteria' (say for example, they stop doing extra diligence like physically visiting places and checking up on random selections of mortgages) ... then their credit ratings become less valid ...
Then you don't have anyone committing fraud - but a cynical failure of the system.
It's the same thing with Forrester and the other firms that give 'grades' on products.
I worked at an F50 and we paid for tons of research from firms like that. They also would review our products and put them in the 'magic charts' of 'winners/leaders and losers'.
It's a tricky conflict of interest ... if you don't buy their products, maybe you won't get good reviews.
Now - that is almost fraud - if there is internal decision making that outlines this, i.e. research sales guys saying 'if you don't buy our research we will give you a bad review' or internal practices to that regard - it's probably illegal - or certainly highly unethical.
But it never got to that. We just bought a lot of research.
It's an issue wherever there is a conflict of interest and it's hard to manage.
This is where the SEC could possibly have more impact/influence - in terms of specifying 'what must be done' in a rating.
Ultimately, the market should correct itself - the 'ratings agencies' should have basically had their credibility completely blown up. They didn't. This is bad.
Do you remember Enron? Arthur Anderson did their books. When Enron blew up - there was no 'regulating' needed. Arthur Anderson lost all of their business, because nobody wanted to have their books 'ok'd' by a company that has no integrity, when what they are selling is 'integrity'.
It would be nice if bankers basically demanded good ratings. The Germans and Japanese lost 10's of billions because they never, ever imagined that Americans would lie about this stuff. Surely they have changed their ops a little bit ... but possibly not enough.
Anyhow - I don't think there was a lot of fraud or malice. Just greed, laziness and stupidity, others are clearly more to blame than others.