There is no word 'snoppy' in English. Perhaps you made a typo, or perhaps you need the urban dictionary category.
The word 'Snoopy' (capital S) is a proper nounthe name of a specific cartoon character.The word 'snoopy' (lower case s) is not a noun, it's an adjective used to describe a noun as offensively curious or inquisitive.
"Park Avenue" is a proper noun, because it is a place. Proper nouns like this should always be capitalized.
It is a proper noun, because it is the name of a specific thing.
proper
Proper noun
Pencil proper or common noun
it's a common noun. a proper noun would be Spider-Man.
Proper noun or common noun
SIM
The noun cassette is a common noun.
a common noun?
Camel is a common noun.