Key Differences:

1. Type of Modifier

   - In adj + N, the modifier is an adjective, giving descriptive information.

   - In N + N, the modifier is a noun, providing specific contextual information.

2. Information Provided:

   - adj + N focuses on qualities or characteristics of the noun (e.g., color, emotion, speed).

   - N + N focuses on the type, function, or association of the noun (e.g., purpose, composition, origin).

3. Syntax and Meaning:

   - adj + N typically describes "what kind of" noun is being referred to (e.g., a "red apple" is an apple that is red).

   - N + N often describes a new concept or entity that combines the meanings of both nouns (e.g., a "tea kettle" is a kettle for tea).

Examples:

- Adjective + Noun:

  - "Sunny day" (A day that is sunny)

  - "Ancient artifact" (An artifact that is ancient)

  - "Delicious meal" (A meal that is delicious)

- Noun + Noun:

  - "Jewel case" (A case for jewels)

  - "Office chair" (A chair used in an office)

  - "Dog house" (A house for a dog)