What is the difference between legal heir and a nominee

The nominee and legal heir are two distinct parties; the nominee may be the legal heir if he or she has been nominated for assets or riches, and his or her name is also mentioned in the will as the clearly specified legal heir. You must be aware of certain important distinctions between nominees and legal heirs: Nominees do not have the same rights as heirs.
Here is a difference between nomination and an heir, according to the ICICI Securities website.

Nomination simply serves as a legal mechanism for the candidate to claim property as the "custodian" in the event that the property's owner passes away. When the property owner dies, only the nominee is eligible to claim the property.
He or she will only serve as trustee or custodian for a short time, until the Succession Act (or Will) establishes the legal heir to the property or estate. Then, in accordance with the law, the nominee will transfer the property or estate to the legal heir or heirs.

Minor children may have nominations for guardians who will be responsible for overseeing their welfare and protecting their part of the decedent's inheritance. For the benefit of children and legal heirs, a family trust or private trust may also be established in many circumstances.

The person who is legally entitled to inherit the deceased person's wealth and property under a signed legal will or otherwise under the terms of any applicable personal succession legislation is known as the legal heir, as opposed to the nominee. The deceased person's Will should clearly identify the legal heir as the primary inheritor. A single person or a group of people can be the legal heir.

The Hindu Succession Act stipulates the following rules for how property will be divided equally in the absence of a will or a named legal heir:
Equal distribution amongst all Class 1 heirs
In absence of Class 1 heirs, equal distribution amongst Class 2 heirs
In case of no Class 2 heirs, distribution amongst Agnates and then Cognates
In case of no one being present, the Government takes the property/ estate of the person deceased.