In Bhagavad Gita, Lord Krishna said..
yajante sattvika devan
yaksa-raksamsi rajasah
pretan bhuta-ganams
canye yajante tamasa janah
Men in the mode of goodness worship the demigods;
those in the mode of passion worship the yakshas and rakshasas;
and those in the mode of ignorance
worship ghosts and spirits.
What about Siddhis meditating on Supreme being? What is the difference between those Siddhis who meditate on the demigods and those who meditate on supreme being? Will there be any difference of the powers?