I have just spent two intereting but ultimately fruitless hours trying to to find out just when the word "solicitor" came to be commonly used. Th ebest info I have come up with was not form the Law websites, but from the history of the Legal and General Assurance Society- an insurance society that was started ni 1836 by five barristers and one solicitor.

The main difference in status between the two branches seems to have been that solicitors dealt directly with the public, and got paid for their work, whilst barristers had to be engaged by the solicitor on behalf of the client to act for them in court, so didn't directly handle "money" as such. Therefore barristers were more gentlemanly than attourneys/solicitors.