How are bacteria and eukaryotes different

 Bacteria- a member of a large group of unicellular microorganisms that have cell walls but lack organelles and an organized nucleus, including some that can cause disease.
eukaryotes- Any of the single-celled or multicellular organisms whose cell contains a distinct, membrane-bound nucleus. Organisms such as animals, plants, fungi, and protists are examples of eukaryotes because their cells are organized into compartmentalized structures called organelles, the nucleus in particular. 
*FROM GOOGLE DICT*

Bacteria does not have organelles and eukaryotes do, eukaryotes also have a more defined nucleus. 

The answer is ozone layer.