As you can see the tail of the black rat is significantly longer than the one of the brown rat. Black rats are much livlier and quicker than brown rats, wich this little fellow showed. Another thing differenting black rats and brown rats are that black rats have larger ears that are not partly covered in fur as the brown rat's. Black rats and brown rats eat about the same things. The nose of the black rat is more pointed and their build is smaller snd slimmer.
Black rats are better climbers than the brown rat.
Their paws are made to be able to climb and they can almost litterary go up a wall. The size of the black and brown rats differ quite much. Fotos taken in London Zoo by Staffan Vilcans and Mia Bruksman. Claire Jordan have a page about Rattus rattus that contains more information.