Long-term illness and injury leave vs medical leave (Human Rights Act)

How does long-term illness and injury leave differ from the current medical leave under Alberta Human Rights Act? My company has long-term disability benefits which an employee may be eligible for after 17 weeks of illness or injury. According to Alberta Employment Standards, employees are protected for a maximum of 16 weeks. What does this mean if an employee is not fit to return to work after the 16 weeks? Could the employer then terminate their position? Prior to Bill 17, I was under the impression that an employer must accommodate the leave of absence until it becomes evident that the employee is not getting better and return to work is not likely. (Approx. 2 years was a benchmark for determining that). I would appreciate clarification as the Alberta government did not exactly provide resources beyond basic information.