Answer:
Plural is when something is more than one. For example, the word, "Carrots" Is plural because it is saying there is more than one carrot.
Possessive is when the subject belongs to someone. "This carrot is Jayden's"
The use of an apostrophe can demonstrate the difference.
"The American Civil War's last land battle, the Battle of Palmito Ranch occurred on the Bank's of the Rio Grande in Texas."
Look closer. It wouldn't be on the Bank, because it is plural. And it certainly isn't possessive because it isn't saying anything belongs to anybody. So, you would correct the sentence to this:
"The American Civil War's last land battle, the Battle of Palmito Ranch occurred on the <u>Banks</u> of the Rio Grande in Texas."