<p>They don't seem to be very different. </p>
<p>Also since the allergy secialty is Allergy and Immunology, would and Immunologist also be an Allergist and visa versa.</p>
<p>Considering I'm studying for a test in immunology tommorow, I can explain this...</p>
<p>You're pretty right in that they aren't really that different.</p>
<p>Basically a rheumatologist is going to focus on autoimmune disorders - the treatment and diagnosis of disorders in which antibodies start attacking "self" tissue. These diseases include not only rheumatoid arthritis, but Goodpastuer's syndrome, Hashimoto's thyroiditis, Systemic lupus and so on.</p>
<p>Allergists are going to focus on the treatment of a different disorder of the immune system. They are focusing on IgE mediated responses that produce reactions that are not a normal part of the immune response. They are going to diagnose, treat and manage these responses.</p>
<p>Immunologists are going to work with a variety of other disorders of the immune system - things that could include immunodeficiencies, myelomas, lymphomas, and certain types of leukemias. They can often work closely with oncologists in this regard.</p>
<p>Residencies in allergy and immunology are going to probably have a significant amount of common ground (since allergy is really a part of immunology), but there is likely some divide that occurrs in the later years of the programs pushing the residents to one subspecialty or the other - all though I'm sure there are plenty of people who do both.</p>