Contrary to the name "Type 2 diabetes" is best described as a category of unclassified types of diabetes.
LADA is an autoimmune disease and is best explained as type 1 but with an "extended honeymoon" period that could last longer than a decade in some people.
As@TorqPenderloin said, Type2 can be summarised as "we don't think is Type1..."
LADA is "Late Onset" type 1
Gestational Diabetes is usually akin to pregnancy hormone induced T2 (which may reverse after pregnancy.)