gameplay discussion- weird case

so i went to normal game picked riven in teambuilder, and turned out to play vs talon

it was fine, i planned that ill go to lane push it a little and get lvl2 faster, then ham turned out that i pushed my lane, killed more minions, and that guy reached lvl2 when i still needed some exp i checked his cs, he barely had 5 while i had 8, so after i had lvl2 i went ham cause i though i can, unfortunately winions interfered (i suck at predicting them, i fought too close) and i died while talon had 10 hp and 3ticks of my ignite left, it was right after i reached lvl2 and he reached lvl3 , survived

the entire game this guy didnt farm much, yet he had at least one lvl over me sometimes 2 i was insanely close to the minions, so i didnt miss any exp and everytime i negaged with him he had to b he had no xp runes nor mastereis, no zilean in his team and always 2 lvls ahead of everyone else

can someone tell me what did he do to get exp so fast without even farming ?