If A had, say, $100,000 cash, A could make an interest free loan to the trust. But the money lend would remain an asset of A. If A were to go bankrupt the $100,000 would fall into the hands of A's creditors.
If A had, say, $100,000 cash, A could gift that money to the trust. If A were to go bankrupt the cash would not imediately fall into the hands of creditors, but could possibly be clawed back as an undermarket value transaction. How long this could be clawed back would depend on how the transfer was structured. Generally first 4 years would be at high risk, but the longer ago the transfer was the harder it will be to claw back. However if the transfer was done to defeat creditors (or 'asset protection') the money could be clawed back indefinitely - under both bankruptcy act and relevant state legislation such as s37A Conveyancin Act NSW.
If A later wants the money gifted back A could request the trustee make a capital distribution. The Trustee will need to determine if it has the power to make this distribution. Another option may be for the trustee to lend money to A. Trustee also has to determine whether it has the power to make this loan, and if so under what terms. It may even be able to to be done at 0% interest. Trustee may also want to take security.
If A borrowed $100,000 and then lent this money to a trust the interest that A pays on the loan would not be deductible. that would be around $5,000 pa at market rates.