That's a bit of an oversimplification. T1 is auto-immune -- the body loses the ability to produce insulin, and you can detect autoantibodies in the blood. T2 is insulin resistance, and generally has no autoimmune component and no autoantibodies present.

Typically T1D comes on all at once; the autoantibodies destroy the insulin producing beta cells and the patient needs exogenous insulin starting immediately. A subset of adult onset T1D displays a much slower progression of the destruction of beta cells. This is called LADA (latent autoimmune diabetes of adults”) or slow-progressing T1D and more recently T1.5D.

Similarly, some T2D patients also show evidence of autoantibodies however their beta cells are still largely functioning.

So now we further split into groups; Type 1–LADA, Type 1.5 or “double” diabetes, and Type 2 diabetes with autoantibodies.

This is a good overview: https://www.diabetesselfmanagement.com/diabetes-resources/de...