Type I diabetes is an auto-immune disease and absolutely must be controlled with insulin injections or insulin pump. The immune system keeps attacking the pancreas until it cannot produce insulin at all and without the injections or pump the person will go in to a diabetic coma and may die.
In Type II diabetes the pancreas produces insulin but the body doesn't respond to it - it becomes insulin resistant. So the pancreas pumps out more and more insulin until it is unable to produce enough insulin.
This explains it very well, but you can see that Type I and Type II diabetes are very different.
http://www.diabetes.co.uk/difference-between-type1-and-type2-diabetes.htm
There is a call for Type II diabetes to e given a completely new name so that is not associated with Type I diabetes at all. It will be interesting to see if that happens.
To complicate it even further, there is a third type, Type 1.5 diabetes.
http://www.diabetes.co.uk/type15-diabetes.html