I think it's the same concept but different uses (LDA vs LDI). The link that kyo posted explains it pretty well. Basically you're trying to stop your immune system from reacting to the Lyme (or whatever other infection) bacteria.
"To further confuse things, another term used for this type of therapy is “low dose immunotherapy” or LDI. This term emphasizes using LDA for more than what is thought of as typical allergies, such as desensitizing the immune response to certain bacteria.
Using LDI for autoimmune diseases and conditions that involve an overactive immune system is a truly unique therapy. It is well established that certain autoimmune diseases, and perhaps most of them, are “triggered” by an initial infection. As the immune system recognizes the infection and mounts an attack there is a cross reactivity with their own tissue. This process is called “mimicry”."
Also, IVIG is related to the blood product immunoglobin, which is completely different