There is no difference in experience gains between Xbox, Stadia, Playstation, and Steam. XP also has absolutely no effect on power level outside of the boost from the artifact. Equipment gains are the main way to increase your power level and PC has no boost in that regard either. Some people just have more time and put a lot more effort into playing the game than others or are good at maximizing potential xp gains by finding activities or repeatable bounties that give a lot of xp and doing them quickly. There are a few people on console that have hundreds of artifact levels just like there are a few on PC that have hundreds of artifact levels. If you do the exact same bounties on console that your friend does on PC and play the exact same activities and kill the exact same enemies and number of enemies, you'd have the exact same amount of growth that your friend does. If none of the variables are different, then the experience gained will be exactly the same. Keep in mind that doing things with others will increase your xp more, including turning in bounties, but not because of console or pc, but instead because there are fireteam xp boosts on the Season Tracker. So if you've been playing solo and your friend has been playing with others, then your friend will most likely be gaining xp because of the fireteam boost. It's not just because they play on PC.