There is no difference between afterward and afterward. Both are adverbs that can be used in the same context. They have the same meaning, which is to mean later. Both of these words are often confused with the afterword. Compared to the other two words, the afterword is a noun.
It is a portion of the book that is at the end of the book. An example of the word afterward being used is "James and Jennifer went to dinner and then had dessert afterward." To use the word afterward, we can take that same sentence and add an S at the end of afterward.