Hello destertnana 1,
Thank you for using JustAnswer Health for your question. As you likely know, this is what the initials stand for regarding the certifications you are asking about:
RHIA - Registered Health Information Administrator
RHIT - Registered Health Information Technologist
The RHIA is basically the "boss" and the RHIT is the "tech" but of course depending on the location, years experience, I'm sure there is some cross over of roles, just like there is for the Associated degree RN and the Bachelor degree RN, which can similarily be compared (perhaps LPN and RN makes a better comparison). The RHIA has more administrative training and experience, while the RHIT is mostly trained to do the actual coding with out the administrative duties.
The RHIA must have at least a bachelor's degree, while the RHIT must have at least an associate's degree.
I have worked along side an RHIT briefly recently while I was doing chart abstraction for a company (actually she worked for the same company as I) and she was doing quite well finacially and as well as travelling all over the US at times when needed. This seems to be a good career right now. I don't know as much about the RHIA, but I'm sure there is the same need, and most likely the salary is higher.
Here are all the details:
Good luck, feel free to reply is you have further questions.