Buying replacement bulbs for my car is annoyingly difficult to figure out.

I ordered "4157" bulbs in white because that's what I was told to order. Except the lens enclosure isn't precolored so I should have bought amber.

I ordered 4157 amber lights, received "3047A" bulbs. But they're marked "also fits: 4157". There's also a sticker: "Replacement For 4157A".

Is the 4157A the same as the 4157? And if this "also fits" why is it marked 3047A?

I'm so confused.