BW:
I think of a rating as something which is attached to something "pre-knowledge", whereas a reputation is something which develops over time & based upon informed knowledge ("after-knowledge").
you are free to assume any connotation you like. but in my view they are pretty much interchangeable. they are both "meta information"-- information about other things or information. a credit rating is in fact a "credit reputation"-- it is a built up credit history over time. maybe you would prefer the term "credit reputation"?
A rating is applied to something (a service or whatever) by only those few individuals who are acquainted with what they are rating.
A reputation is accumulated by the impressions made upon larger numbers of individuals - a general population not necessarily employed to collect these impressions - but who have nevertheless sufficient exposure to and acquaintanceship with the person/service/etc. to make an informed conclusion about it.
A rating can make a statement on what something "is" or is expected to be (eg, general in content vs explicitly sexual), where a reputation reflects on past behavior.
oh, ok, a reputation would refer to a person, and a rating might refer to a thing. a valid distinction, but not necessary for a system that is purely electronic. people and things could be rated interchangeably. but of course in the "people" case you are going to get a lot more political fire. issues like libel and defamation come up. it will be interesting to see how they are resolved. again, I suspect in the future the distinctions you refer to are going to blur. there will just be ratings of all kinds of things, including people. some ratings will be based on expert opinions, some will be based ona consensus of opinions measured somehow ("reputation"), some will be purely objective such as "score on last driving exam", etc. of course all kinds of nasty issues like privacy etc. rear their head. I don't claim to have an answer or clearcut guidelines for all this.