Fremont vs Austin Factory for 2026 Model Y

Which factory is better for the 2026 Model Y and are there any advantages of one over the other and are they both using megacasting and 4680 batteries? Are most of the 2026 Model Y coming out of the Fremont factory? I just placed an order and the vin number shows it’s built in Fremont. I’m in the Boston area. My 2023 Model Y was built in Austin.