Take note also that BTC transaction fee isn't fixed, it depends on the size of your tx and the BTC network congestion as of the time of broadcasting your tx.
Neither is the lightning fee. It is based on the amount you're moving. If you try to move something like 0.01 BTC via lightning, it'll be way more than the on-chain equivalent.
Trying to explain LN in just a few lines, I'm not sure it is possible
I think I can do it in one sentence too, in laymen terms: lightning is a second layer solution which takes advantage of the Scripting language of Bitcoin and makes it possible to trustlessly transact off-chain as long as the peers share a funded multi-sig address.