Honolulu time is in the Hawaii-Aleutian Standard Time (HST). They don't practice Daylight Saving Time, so they are 2 hours earlier than Pacific Standard Time and 3 hours earlier than Pacific Daylight Time.
Honolulu is in the same time zone as all of the Hawaiian Islands, so you won't find a time difference within the islands.
Be sure to check the Hawaiian time when you are calling vendors or sending emails. They will work typical hours, but they will be working within their time zone. It can be very convienant though, because you will still be able to communicate with them late into the evening depending on where you are located.