Yes there is a difference. The bump map simply requires a greyscale image and a low poly mesh. The normal map generally starts with a high poly and low poly mesh and the high poly meshes detail is baked onto the low poly mesh. Both are just a lighting trick there is no actual geometry. From your description it sounded like you had a hi-poly mesh and wanted to create a normal map.

You should be aware that a bump map will only create the illusion of treads it will not actually displace the geometry so if you get to close or you view the treads edge on you will see that there is no actual tread geometry.