AirPod Packaging

How can you tell the difference between Gen 1 and Gen 2 AirPods by looking at the packaging?

The model with the wireless case is easy but with the similarities between the wired models being so close it's hard to tell by just looking at them. I will need to replace my 1st gen models soon due to the battery's short life now. I wouldn't want to end up with the gen 1 model because a retailer still has old stock.