What is SAL?
This is a service where international mail is handled as surface mail in both Japan and the destination country and as airmail between the two countries. The service is faster than surface mail while the cost is lower than airmail, quotation from Japan Post.
Estimated shipping duration to the U.S.A is 2 to 6 weeks. SAL doesn't have tracking service and insurance. But you can put them on your items by paying additional 5 dollars.
What is EMS?
EMS is Express Mail Service which is more reliable in speed and security than any other shipping methods from Japan. Estimated shipping duration to the U.S.A is about 1 week.
It also has tracking service and Insurance up to 20000JPY, approximately 210 USD.
What is E-Packet?
E-Packet is newly provided shipping service by Japan Post. It has tracking service and Insurance up to 7000 JPY. It takes 1 to 2 weeks for delivery.