FreeBets are available only on sport betting to place single and multi-bets, but not system-bets. There aren't wagering requirements, but you do need to use the whole FreeBet at once. If you have one to use, you'll see it in the upper right-hand corner of the sport betting pages.
Free Spins are spins to use when playing Casino. They can be available immediately or it might be required to make a minimum deposit to activate them. Also, they might work only on specific slots. Specific requirements will be visible after clicking "More Info" in the Offers" section of your account.