Hard links vs. Soft links

[For Mongo]

What is the difference between a hard link and a soft link?  Besides the fact
that a hard link seems to make a copy of the file, while the soft link just
points the OS to the real file.  In broader terms, my question is this: I have
a Tektronix 4301 that has the commands ls, ll, lf, lg, and lx, all of which are
derivatives or ls.  They are all the same size, and they are all linked
together.  When I had a system error and all the links were destroyes, I
deleted them all, except ls, and re-linked them using soft links.  I saved
about a quarter of a meg of disk-space.  I have come across some other files
that are the same way, and am wondering how much space I can save, compared to
how much system performance I will lose.  Can anyone tell me how soft links vs.
hard links will affect system performance. 

Thanks,
Steve P Potter
Systems Manager
Mission Research Corp