What is the size of those 4000 containers? Are they 20ft containers, 40ft containers, both...?
Let me simplify it for you. Go to Google and type "is the number of containers the same as teu"
If you managed to do this correctly your answer will be:
No, the number of containers is not the same as TEU (Twenty-foot Equivalent Unit); while the number of containers simply counts the total number of containers, TEU is a standardized measurement that considers the size of each container, essentially equating a 20-foot container to 1 TEU, and a 40-foot container to 2 TEUs, meaning a shipment with one 40-foot container would be considered 2 TEUs even though it's only one container.
So when one article only says 4000 containers and another only says ~6000 TEU's you do not have enough information to make a comparison.