Lasting powers of attorney
These are made when you have mental capacity and fit in two categories.
a) Health and welfare
b) Financial Matter i.e. Managing banking, paying bills, buying/selling property
You can do both or one of the above an attorney must be appointed.
Once mental capacity has been lost and there is no power of attorney in place you may then apply to the court of protection who then appoints a deputy who manage the affairs
General Power of Attorney
There is a wide variety of reasons a general power of attorney is given, i.e. to be used abroad to sell property to manage the affairs for short period of time if you lose mental capacity you could not use this if you lose you capacity to make your own decision.