What is the difference between the term ‘completion certificate’ and ‘occupancy certificate’?

Section 2(zf) and section 2(q) respectively, define ‘occupancy certificate’ and ‘completion certificate’. Occupancy certificate relates to the occupation of the apartment/building, which has provision for civic infrastructure such as water, sanitation and electricity and is habitable. Completion certificate relates to the completion of the entire project certifying that the project has been developed according to the sanctioned plan, layout plan and specifications, as approved by the competent authority.