A package holiday is a well-established and well-understood way of booking a holiday where all the arrangements are made for you by the travel company.
If you're talking about a 'holiday package' you'll have to explain what you mean by the term.
I'm with Raymott here. To me, if you are planning to visit, say, Egypt, you could choose between the "all included" package and the "all included except the hotel spa" package, for instance. IMO, both can be called "a package holiday" with the same destination, but different prices.