In Diablo II damage listed in your statistics screen can be far from the damage you actually do to monsters.
Lightning Strike launches a Chain Lightning when you hit. Which inflicts listed damage given number of times (number of hits).
Lightning Fury works the other way. First of all, highest possible Pierce (with skill alone, or skill+Razortrail is up to you) is a must for LF. When you throw a LF into a crowd, on first hit it releases a bunch of lightning bolts, pierces, releases another bunch, pierce again, more bolts, etc.
LS does hit multiple targets as well, but every its hit (up to listed maximum) is literally a hit of a single target.
A secondary LF bolt (I mean the bolt that is launched from a target that was hit) pierces and can hit additional targets. And there are many of theese bolts per burst, just as many bursts per LF throw. That's why LF is such a great crowd killer - it hits much more times, than LS do. Requires a tight and big crowd, though.
You say that LS is good at killing cows? One good LF throw can kill a crowd of cows in 1 hit, leaving several heavily wounded survivors. Theese, I beleive can be effectively finished with LS.