I am not aware of existing tools/code to do that. But if you are using apache POI and want to do it on your own, you can do like as follows
1. Extends HSSFRow class and override equals() method and implement your code to compare two rows. OR write a utility method in your existing class which take two HSSFRow object and compares two rows, returns true if they are equal else false.
2. Use HSSFSheet.rowIterator() to get the rows and loop through the rows of your document and call the equals() OR the utility method to compare
Hope it gives some start to solve your problem.