eq { diff { hop { filter_eq { all_rows ; name ; northern eagle } ; year } ; hop { filter_eq { all_rows ; name ; northern hawk } ; year } } ; -15 years } = true
select the rows whose name record fuzzily matches to northern eagle . take the year record of this row . select the rows whose name record fuzzily matches to northern hawk . take the year record of this row . the second record is 15 years larger than the first record .