roblox has evolved so much from what it was before that it now feels less like a game where you build little games with lego bricks and lego-like characters and more like a game engine in general where you can make realistic environments with any sort of characters and make money from it, plus like mr opioid and trogtor said, roblox is constantly being updated by a company that's worth millions/billions of dollars.
blockland is an indie game that keeps it's lego toy style consistent and it's creator has decided to stop giving it major updates for a long while.