Professions are best described by the skills that are associated with them; a profession may have more than one guild that can be associated with it. Therefore the profession of the Seer not only encompasses the Seers' Guild of Thakria, but is equally the domain of the Astrologers in Parrius, and the Mystics in Mercinae both seeking knowledge of the magics stored within the astral plane. There will come a day in your Avalon life that the most important decision of your career will have to be made; that of a profession to which you will apply yourself utterly both in mind and in spirit. It is within the walls of a guild that you are likely to be stood in good stead for future adventuring. Making the correct choice cannot be underestimated in importance.
Those still in the novicehood phase, prior to beginning a guild apprenticeship in earnest should look over HELP SELECTIONS to learn about ways to get a short "sample" of each profession - before deciding on the long-term guild and professional career.