How do an attributive noun (noun adjunct) and an adjective differ in the case when both forms exist and they synonymously function as a modifier?

Question

i.e. How do ancestor worship house and ancestral worship house differ?

Definitions

ancestor [noun]

• a person, typically one more remote than a grandparent, from whom one is descended.
• an early type of animal or plant from which others have evolved.
• an early version of a machine, system, etc.

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ancestral [adjective]

of, belonging to, inherited from, or denoting an ancestor or ancestors.

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According to Google Ngram Viewer, the use of attributive noun in this case (ancestor worship) is more prevalent in modern times than the adjective form (ancestral worship).

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Pre-emptively tackling the existing questions that are or may be similar:

English SE question: Adjectives versus Noun Adjuncts [duplicate]

I tried looking at this post but it seems argumentative in nature and it is not helpful for me in practice because it focuses more on the meta side of the question, with answers affirmatively conclude that an adjective abstractly different from a noun adjunct with logical proof on the meta side and some prescriptive examples of attributive nouns that cannot be synonymous with its adjective counterpart, like "chicken soup" because there is no adjective form for the term "chicken" or "horse racing" because there is no adjective form for the term "horse". In my instance, "ancestral" is an adjective word class of ancestor and both the adjective form and noun form can be used as a modifier.

English SE question: What's the difference between adjuncts and modifiers?

I don't know if the answer in the question answers my question because it conclusively state that adjuncts (presumably include noun adjuncts?) are supplements and they cannot/are not integrated into the syntactical structure of a sentence, but rather as interpolations or appendages supported with several examples. However, in my instance, "ancestor worship house", the noun adjunct is not an interpolation/appendage, is it?

Answer 1

Unfortunately, in 1., you have chosen three nouns, two of which - ancestor (n.) and worship (n.) - are attributive.

The guidance is that noun1 + noun2 + noun3 = noun3 that is associated in some way with noun2 that is associated in some way with noun1.

A house that is associated in some way with worship that itself is associated in some way with ancestors.

ancestor worship house = a house that is associated with the worship of one’s ancestors.

OED

Ancestor [worship](n.)

C1. Chiefly Anthropology. As a modifier, used with reference to various religious practices or beliefs based on a devotion to one's ancestors, as ancestor cult, ancestor spirit, ancestor worship, etc.

1829 J. Bentham Justice & Codification Petitions iii. 204 In ancestor worship, how this our country has at all times vied with China, is no secret to any one.

2002 G. Betty Comanche Society 194 What most students of American Indians fail to understand is that ancestor worship..is at the root of all religious behavior.

ancestral (adj.) 1. Of, relating to, or inherited from an ancestor or ancestors.

1958 C. Achebe Things fall Apart xiv. 118 Uchendu took the hen from her, slit its throat with a sharp knife and allowed some of the blood to fall on his ancestral staff.

2005 High Country News 21 Mar. 6/1 Indian tribes are making headlines for taking control of their ancestral lands.

True adjectives are more direct or definitive -> adjective + noun = noun that is adjective.

Ancestral worship house = A house used for worship that was owned, controlled, or used, by one’s ancestors.