Ketoacidosis and ketosis are health states; one is healthy while the other is dangerous.
When our body burns fat efficiently without muscle atrophy, we are in a state of ketosis. This is healthy. When our body has trouble burning both fat and glucose, we are in a state of ketoacidosis. Muscle atrophy occurs, and the blood becomes acidic. This state is dangerous.
A major reason low-carb diets are recommended is that ketosis can occur. However, since ketosis sounds like ketoacidosis, people associate low-carb diets with the state of ketoacidosis and think it might be unhealthy.
The following infographic by AuthorityDiet.com distinguishes side-by-side ketosis vs. ketoacidosis health states.