Make notes of who is exactly named for what. As @Mad Mike said, Power of Attorney only matters while the person who wrote the Will is alive. When the hospital informed my sister and I my Dad wasn't going to live much longer we took action using Power of Attorney. If he had passed it instantly would have been a useless piece of paper and Executor status would not have given us the authority to make those changes to the estate.Yes, it's never easy. I'll check out what they wrote and then see what potential issues are.
I'm ok with them putting me up as we've talked with my dad multiple times since they didn't have an updated will since the 90s.
TLDR:
Power of Attorney (2 separate types) manages the assets (property, cash, etc) and person (make health decisions) if said person is incapable of rendering their consent; parent unresponsive in the hospital needing a surgery for example.
Executor is responsible for carrying out the 'Will' of the deceased. You do all the leg work with creditors, write the checks to creditors and beneficiaries, dealing with final tax return to CRA and getting the clearance certificate (if you don't have this and CRA judges the estate still owes they will come after YOU.)
Beneficiary sit back and gripe at the Executor to hurry up and pay you.
Finally do not be afraid to ask a lawyer for advice. For example, you have Power of Attorney and the individual is going to pass soon, what action would they advise to be taken while you have the power to do so? We did and we saved money.