Short answer: Grant = up to $10,000 cash. Loan = buy with 5% deposit. You can use both.
The First Home Grant gives you up to $10,000 cash toward your deposit. The First Home Loan lets you buy with only a 5% deposit instead of the usual 20%. You can use both together. Think of the Grant as free money, and the Loan as easier lending rules.
House Price: $600,000
Standard Deposit: $120,000 (20%)
First Home Loan Deposit: $30,000 (5%)
First Home Grant: + $5,000
Total You Need: $25,000