You can read the full details in our Flight Reward Rules.
Saver rewards offer the best value when you travel during lower-demand periods or when your travel dates are flexible.
Flex rewards offer greater flexibility when making your travel plans. They cost more Skywards Miles than Saver rewards, but they offer you more seat availability during high-demand periods and on high-demand flights.
Flex Plus rewards offer you even more reward seats during high-demand periods and on high-demand flights.