So on chain is the way the media says it long time to settle (10min) lightning is instnat settlement for micro payements i too am learning and so this i have gained as far as submarine swaps I usually use Muun wallet right now although I keep seeing how fees r crazy high to do so have been looking into running my own lightning node have btc node thru umbrel now just need to set up lightning and use that u would load up with lets say 2 million sats and use for spending and recieving payements where u urself control the fees also seeing comment earlier u can convert coins from on chain to ln it seems with the node ok ok ! Hope this helps!