If a supplier advises an ETD, this is the date the goods will leave that supplier's premises.
On the other hand, the ETA is the date the goods will arrive at the destination, or in the case of importing/exporting, it is the date it will arrive at the destination's port/airport.
It's important to distinguish between the two, as the term 'delivery' can mean different things to different people.
The following example shows the importance of distinguishing ETD and ETA. A Purchasing Officer places an order for fibre-optic cable from a supplier in China. The supplier advises an ETD of December 2nd. The Purchasing Officer then advises the sales department that the ETD on the cable is 2nd December. The sales department misunderstands the meaning of ETD and advises the customer that the cable will be delivered to their store on the 2nd of December!!! On the 3rd of the December, the customer phones up the sales department asking where their cable is. The sales department ask the Purchasing Officer where the cable is and the Purchasing Officer explains that the goods have only just left China on seafreight on December 2nd, and therefore won't arrive (ETA) until January 5th. Not a happy customer!
Everyone has their own terminology for deliveries, so communication is important. This is highlighted in the following article called The Heartache of Delivery Dates!