Nomination

According to law, a nominee is a trustee, and not the owner of the assets(Movable/Immovable). In other words, he(nominee) is only a caretaker of the assets.
A Hindu female (Wife) along with her children are deemed to be Class I legal heirs of a Hindu Man.

The nominee will only hold the money/asset as a 'trustee' and will be legally bound to transfer it to the legal heirs.

For most investments, a legal heir is entitled to the deceased’s assets irrespective of an appointed nominee.

Generally banks discharge their obligations by releasing the monies to the appointed nominee, though he(nominee) may not be the legal heir. The nominee, in turn, is supposed to hold the proceeds in trust and the legal heir/(s) can claim the money.

A legal heir will be the one who is mentioned in the will. However, if a will is not made, then the legal heirs of the assets are decided according to succession laws, where the structure is pre-defined on who gets how much.

It is essential that one needs to execute a will. It is the ultimate source of truth and replaces the succession law. Succession law depends upon the religious faith of the deceased person and varies for different religions in India.