If we are talking specifically about how the games/players are softer:
Online the standard preflop open size is 3x
Live it is between 5x-8x
Online roughly 5% of the population still donk bets
Live over 80% of players still donk bet
Live a full ring table will often have 4-5 preflop limp call stations
Online you don't see very many Limpers
Live you get to physically see which players are drunk.
Online you are guessing.
Live you can often sneak a peak at other ppl's cards as they are being dealt, especially the people beside you. At least I do when I can. I know, shame on me.
IMO, these are the main reasons why live play is so much softer. Add in alcohol, marked Cards, chip signalling, etc... As well.