Plural or genitive?
I'm having difficulty determining if a word is plural or in genitive case. It seems the word endings are the same if they are plural or genitive.. Is this correct? If so, is the only way to decipher if something is in genitive case is by the "y"?
Here's a good chart:
The genitive singular and the nominative plural are the same in the feminine and nueter form, but they are different in the masculine.
As for differentiating between them, you just need to know when to use the nominative versus the genitive. "у + gen." is one of them.
Context. Certain words can only ever take the genitive case. Such as нет, у, из, and many others: http://www.alphadictionary.com/rusgrammar/prepgen.html
Also its function in the sentence. Off the top of my head, I can't think of any examples where a nominative plural could replace a genitive singular and still make sense.
Yes, most of the common genitive singular endings (except for masculine) are identical to the nominative plural endings. But there's always a way to decipher which one is used.