this is my understanding:
POF before landing:
VO is concern whether the applicant have the required fund or not and does the fund solely belongs to them, not borrowed. They ask us to provide the bank letter, bank statement to prove that and they investigate.
POF after landing:
IO is concern whether we can bring the required fund to canada 0r not. Because canadian government doesn't provide any financial help to applicant to settle, except refugee applicant. It is not possible to withdraw money from the home country bank sitting in Canada (country specific regulation applies), unless the funds are with a bank which have a presence in canada (ATM withdrawal) OR have a travel money card from your the local bank, bank statement will be accepted; the fund can be in local currency.
In short, Immigration officer wants to see whether how easily you can have access to the fund.
Quoted from CIC website:
How much money you should bring
Research how much it costs to live in the place where you plan to settle in Canada.
Bring as much money as you can to make moving and finding a home in Canada easier. Canadian customs regulations require you to declare if you're bringing more than CAN$10,000 into Canada. If you don't tell them, you may be fined, and your funds could be seized. This includes:
- cash
- documents that show property or capital payable to you, such as:
- stocks
- bonds
- debentures
- treasury bills
- documents that guarantee payment of a set amount of money, which are payable to you, such as:
- banker's drafts
- cheques
- travellers’ cheques
- money orders.