Each has different consequences. An Express Entry profile lasts twelve months, and if it expires you simply submit a new one. An invitation to apply (ITA) has a strict deadline; if you cannot gather documents in time, it is generally safer to decline and return to the pool than to submit an incomplete or rushed application. A provincial nomination also carries an expiry date. Some provinces will extend it if you ask before it lapses, so contact them early rather than letting it quietly die.