based purely on the launch page for mtgo, yes. They’re both up to date.

Arena gets all Standard legal cards but supplementary decks and sets only sometimes. For instance, the Edge of Eternities Commanders are on Arena but none of the other cards from the commander decks were added. Arena did get Lord of the Rings and Modern Horizons 3 but never received any other supplemental sets (though they haven’t really printed any new ones lately so that hasn’t mattered).