Muta’a is that contract marriage in which a time frame or limit is set. And this time frame can be from an hour to a year. There’s no limit in muta’a that it can be for a short time or for a longer time.
After the end of the contract of muta’a, man pays the women the amount (Meher). The contract can be ended before the time by the man, but for that he will have to pay more amount to the women apart from the Meher.
Another important thing in muta’a is that the child in result of the muta’a will not be a partner in the inheritance. If the man has accepted the responsibility of the child in the contract, then he will have to look after the child, and if not then he will not be responsible for that child.
If the woman is already married then she can’t have this contract, the man on the other hand can. This marriage is only permissible in the Shia sect while the Sunni sect have put it with the level of a rape and have held this illegal.
As per the Pakistani laws, non-Shia man and woman can’t have this marriage.
Nikkah is that marriage contract in which man and woman are married together without any time frame or limit. Although in Nikkah marriage, both man and woman have the right for separation, even if that they separates within an hour.
Every Muslim, be it of Sunni sect or Shia sect, all are agreed that Nikkah marriage is right and according the Sunnah.