* Proper Noun: This refers to a specific person, place, or thing (e.g., John, London, Eiffel Tower). They are typically capitalized in English.
* Noun: This is a general term for words that represent people, places, things, or ideas (e.g., dog, city, happiness).
* Nominal: This is a broader term that includes nouns, pronouns, and other words that function similarly to nouns in a sentence. For example, a gerund (e.g., "running") or an infinitive (e.g., "to eat") can function as a noun.
If you could provide more context or an example of what you're referring to, I might be able to help you understand the specific grammatical concept you're looking for.