MAC= Mycobacterium avium
MAI= Mycobacterium intracellulare

Both are considered NTM. Exposure can vary by geographic location. Here is a snippet of that description from Dr. Falkinham's research on NTM (2021).

Geographic Distribution of Mycobacterium Disease and Species in the United States.
The prevalence of NTM disease across the United States is not uniform, but exhibits “hot spots” and “low spots”. Florida, Louisiana, Santa Barbara, Philadelphia (Lande et al., 2019), and New York City are hot spots, while upstate New York and the southwest are low spots (Adjemian et al., 2012). High soil moisture content and humidity are strong predictors of NTM presence. High NTM numbers are also associated with recirculating hot water systems in hospitals and high-rise condominiums and apartments.
Distinct NTM species also have unique distributions. On the eastern coast of the United States there exists a “Fall Line” that separates the geology of the rocky Appalachian Mountains (Piedmont) from the sandy coastal Tidewater region. Cities on the “Fall Line” include: Philadelphia (PA), Georgetown and Richmond (VA), Fayetteville (NC), Columbia (SC), and August (GA). Florida is entirely to the east of the “Fall Line”. To the east of the “Fall Line” patients are more likely to be infected with Mycobacterium abscessus, while to the west of the “Fall Line” patients are more often infected with members of the Mycobacterium avium complex (MAC). One of the current objectives of the Falkinham Lab is to find out why.

You can find the full paper by searching the subtopic in the group Bronchiectasis and MAC. Perhaps others will weigh in. I do not know what the treatment differences are and if it's possible to have both together. Does this help?

From Wikipedia Mycobacterium avium-intracellulare infection (MAI) is an atypical mycobacterial infection, i.e. one with nontuberculous mycobacteria or NTM, caused by Mycobacterium avium complex (MAC), which is made of two Mycobacterium species, M. avium and M. intracellulare.[1] This infection causes respiratory illness in birds, pigs, and humans, especially in immunocompromised people. In the later stages of AIDS, it can be very severe. It usually first presents as a persistent cough. It is typically treated with a series of three antibiotics for a period of at least six months.