Hard links share the same data blocks on the hard disk.Where as for soft link seperate file is created.

Hard link: Associate two or more file names with the same inode.Where as soft Link is a small file pointing to another file.

Both as same in case of implementation, only difference is in the size of new file created.

Hard Link create a new seperate file and that is not related with old file.A soft link contains the path to the target file instead of a physical location on the hard disk.