What is the exact definition which differentiate freehold and leasehold land?

The land laws of Malaysia are governed by the National Land Code, 1965 (Act 56 of 1965). Section 40 of the National Land Code, 1965 states that all state land belongs to the state authority.

When state land is disposed off by the state authority to an individual in perpetuity for an indefinite period, this land is now granted as freehold title.

When the state land is disposed of by the state authority to an individual for a term of years, by virtual of law, not exceeding 99 years, this land is now granted as leasehold title. 

Upon expiry of the period of the lease, the land should be reverted to the state authority. The owner will then have to either apply for a renewal of the lease before its expiry or apply for a fresh alienation if the lease has expired.

These will involve the payment of a hefty premium which would be close to buying the land all over again with perhaps some discount.