The difference between inheritance and gift is that the heir is the legal heir or one of the heirs of the testator, and the recipient of the gift is someone other than the legal heir.
In this topic, children are the legal heirs of parents and the first heirs. Therefore, after the death of parents, the property owned by children is considered as inheritance, not as a gift (bequest).
Attached, Baidu Encyclopedia's explanation of "legacy":
Legacy refers to a civil legal act in which the decedent gives part or all of his legacy to someone other than the legal heir through his will.