ade99,
Don't really understand your question here...
If you're flying from HNL-KOA-LIH, you will need to fly Aloha or Hawaiian Airlines and spend the "extra couple of hundred". There is no other way to get from island to island.
As for similarities, you'll find much information about the two interisland services by utilizing the search feature of this board. Bottom line is that you're flying newer planes on one, but everything else is pretty much the same.
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There is a lot of valuable information that has already been posted on your topic
You can find this information by utilizing the "search" feature on menu bar on this page. Then search for your topic and you should find the information you're looking for.