Lawyer is the general term designating a person versed in the principles of law and authorized to practice law in the courts or to serve clients in the capacity of legal agent or adviser.
Counselor, barrister, counsel, and advocate name a lawyer who has acquired the right to plead causes in open court or whose specialty is conducting and arguing court cases.
Counselor is the usual designation in the United States for a lawyer who accepts court cases and gives advice on legal problems. The corresponding British term is barrister, with, however, special emphasis on court pleading.
Counsel may be used as the equivalent of counselor; it, but not counselor, is also used collectively.
Advocate is in its implications the equivalent of barrister and counselor, but it is used as a designation in countries (as Scotland) in which the legal system is based on Roman law and in a few special courts. Attorney and solicitor are applied chiefly to a lawyer who serves as a legal agent for clients, transacting their business in specific courts (as probate court). Other powers vary with the law of the state or country.
Attorney is often used in the United States as equivalent to lawyer, but the term may be used more precisely to denote a legal agent who acts for a client (as in conveying property, settling wills, or defending or prosecuting a case in court).
In England, the term attorney has been supplanted by solicitor, with, however, emphasis on the transaction of legal business for a client and the preparation of cases for trial as distinct from actual court pleading.