In the Buddhist precept it teaches us to 'abstain' and 'refrain'. How is this abstention is different to suppression? It's good to practice with understanding and wisdom but most people are still practising, some people are naturally good in practising some precepts but not the other precepts. Is it true there is an element of suppression in the practice until we reach the final goal? Why should someone follow and practice the Buddhist precepts (5, 8, 10 or hundreds of precepts) if there is no suppression?
1. How is abstention different from suppression?
It is not. Suppression means "preventing the development, action, or expression of (a feeling, impulse, idea, etc.); restrain" 1, so they are actually synonyms.
(In case you are referring to the psycho-analytical concept of repression, instead of suppression, then abstinence is indeed different from it since repression is applied in a different context and from a different point of view.)
2. Is it true there is an element of suppression in the practice until we reach the final goal?
I'd say suppression (as defined above) is mostly useful in the initial phases of developing morality. As one progresses, there will be no more suppression since the act of abstaining will be implicit in the use of alternative skillful actions. (For example, instead of just abstaining from punching someone when one gets angry, one may foresee the upcoming situation and take appropriate measures like avoiding or seeking mutual understanding. Technically, one is still abstaining but this type of action is more refined and has no element of stopping a punch from happening when anger has already entered one's mind.)
So I'd say, no, it is not true.
3. Why should someone follow and practice the Buddhist precepts (5, 8, 10 or hundreds of precepts) if there is no suppression?
As I pointed above, suppression and practicing the precepts are the same in the beginning. After that initial stage the precepts are still being followed but there will be no suppression.
This leaves this specific question (3rd question) meaningless. If this was not the type of answer you were looking for in this specific question, I suggest clarifying it a bit since I had a bit of trouble understanding it.
**Is it true there is an element of suppression in the practice until we reach the final goal? **
Yes there is an element of suppression until we reach the final goal but it is more a question of intensity.One starts with suppressing a lot then it gradually lessens to not needing to suppress anything anymore.Not needing to because at some stage insight would have arisen and uprooted the defilement from its root or weakening it considerably.
For example one may use the Jhanas as a means to suppress the hindrances and to let insight arise.Once insight has arisen then the hindrances can be eradicated.Same goes for practicing the precepts as a form of restraint. Precepts deals with the coarser hindrances and the Jhanas deal with subtle hindrances.
Suppression of defilements is needed in the path because wisdom,which is the only thing that can eradicate defilements, cannot arise when one's mind is running around with defilements in the first place.