I use all three levels in an appropriate manner
= lol - smiling to small chuckle
= lmao - actually paused while reading and then laughed out loud
= lmfao - slapping my knee, grasping my chest in hysterical laughter
I am making a joke, or am responding to your joke with laughter;I got your joke.
I may or may not be having a cheeky chuckle at your or someone else's expense, even mine
but I am a laugh out loud kinda person in life as well