There are some very close similarities but also some drastic differences. For similarities, there are a hero who builds a boat to preserve those chosen by a god. They build the boat with levels inside and seal it with bitumen. Both gather his family and animals in the Ark. The floods come. After the flood, they dismebark and sacrifice to the gods. Those are the broad similarities.
The differences, however, are more striking.
- Genesis is monotheistic. It is Elohim who sends the flood and tells Noah to build the Ark. In Atrahasis, the nasty and capricious god Enlil sends the flood while his opponent Enki warns Atrahasis.
- The reason for the Genesis flood is that man is very wicked. In Gilgamesh, Enlil decides to flood the world because men are disrupting his sleep.
- In Genesis, Elohim tells Noah directly what to do. Enki whispers to Atrahasis through a wall of reeds because he swore to Enlil that he would not warn people.
- Throughout the flood, Elohim is depicted as in charge and in control. The gods of Atrahasis fear the flood waters and sit in hunger and thirst.
- The flood in Genesis lasts 40 days and nights and takes time to recede. Atrahasis' flood lasts 7 days.
- The sacrifice in Genesis is to give thanks that they were chosen to be preserved. In Atrahasis, they sacrifice to feed the gods, who forgot that without man to sacrifice animals to them, they would starve.
There is a comparison of multiple flood accounts from the ANE here. However, in the Bible column, they mention a revolt of giants (with a question mark) and that it was both sin and giants that prompted Elohim to send the flood. The giants are briefly mentioned in Gen 6 but the flood is stated to be because mankind has sinned continually.