The difference is that sales tax is a tax on the customer, but GET is a tax on the business. The rate is a maximum of 4.166%.
If a Hawaii business ships the goods directly to the customer’s out-of-state residence, then the sale is exempt from GET and the business may claim a deduction.
Follow this link for good explanation of GET from the Hawaii Department of Revenue.
See all the Zip2Tax solutions for Hawaii sales taxes here.