Respect must be earned, but honesty should always be our policy. People and wall are concrete nouns. Home run is a compound noun. Salt Lake City are compound nouns. Respect, honesty and policy abstract nouns.
Compound nouns can also be concrete or abstract.
Three other specific classifications for nouns are collective nouns, count nouns and mass nouns. Collective nouns name groups as team, class and choir. Count nouns can be counted as one boy, six sheep and many days. You can use a, an, many or a number before it. Mass nouns are not countable as gasoline, water or dirt.