what is the difference between ext2 and ext3

1、ext2 used to be the most common Linux filesystem
2、ext3 is based on ext2
3、Same on-disk structure
4、ext2 can be converted to ext3
5、ext3 can be mounted as an ext2 file system
6、ext3 is a journaling filesystem，Preserves data integrity better than ext2，Faster and safer fsck after system crash