提早and提前just have a little difference. 提早:shift to an earlier time / before one's time ;(提早can use when you say some thing about time) 提前:be earlier than planned or expected(提前can use when you say some thing like plan ,exam, notify,etc) 发货and交货 发货:sent out goods (the goods just send out,you can not see or touch it yet) 交货: deliver goods(the goods is arrived,you can see or touch it now)

They can be used interchangeably as far as I know: 因为大家已经到了咱们将提早开始。Because everyone is already here we will start earlier. 你的包装提前准备好了，目前等待发货。Your package has been prepared in advance and is awaiting shipment. 能不能提前发货？我明天需要这个东西。Can you ship earlier? I need this thing tomorrow. 卖家能提早发货吗？ Can the seller ship earlier?