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Light restrike on compact fluorescent reduces efficiency. A linear tube with a good reflector will have much less restrike than a twisted CFL. So 10W CFL does not necessarily equal 10W linear fluorescent.
CFL bulbs tend to have very poor power factor as they have very simple ballasts. Separate ballasts are more efficient and can have PFC built in.
Watt for watt the highest output fluorescent bulbs are the linear T5 type. Very narrow diameter combined with a good reflector makes for very little restrike and the most efficiency.
The phoshphor on the bottom of a twisted CFL tube is too thick as well, if you look closely at it you can see where the phosphor settled Better care is typically taken for straight tubes because it's easy to just rotate them to distribute the phosphor.