Depends on how you look at it, De-Ting.
A "permanent" position means that if you apply for and "win" the position, it's yours to keep. For example, your chances of being made redundant decrease greatly. If your position or/and unit is made redundant, you still have a "job" and are still employed, which means your organisation will have to find you another position, as similar as possible, of equal pay level.
While they do this, you don't work and you keep getting paid. If they can't find you a position, then you will have to resign, however you will be paid out a large amount of money, including all your saved recreation leave.
Your chances of being fired also decrease dramatically. Basically to get fired from a permanent position, you have to do something really, really bad.
Furthermore by being in a permanent position, this enables opportunities for professional development. For example, you might be in a permanent position and you might see a job that's a twelve month contract, albeit much better pay. You are allowed to apply for this job and if successful, you can transfer there for twelve months, and you will not lose your previous position. Your previous position will then be temporarily filled for twelve months, then when your contract is over, you can return to your previous position/job.
If you're on a contract, it's easier to get fired, it's like being on probation, so to speak. Furthermore, if your job or/and unit is made redundant and you're on a contract, well... you'll be completely out of a job, no pay out. Furthermore if you're on a contract for say, twelve months, and the twelve months reaches its time, your employer may or may not recontract you. This will depend entirely on the business of the budget as well as your performance as an employee. Sometimes an employer may not be able to recontract staff due to budget constraints. If said staff member is really shit, then the employer won't recontract them because well, they're shit.