the difference between 'no longer' and 'anymore' is rather difficult to determine as they almost have the same meaning.
One thing I observe is the positioning of each word in a sentence:
"no longer" is mostly positioned in the middle of the statement, while
"anymore (also any longer) is positioned at the end of the statement.
ex:
"I no longer eat seafoods."
"I don't eat seafoods any longer."
:)