I think a pinnacle would be the top, probably a pointed one.
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AngliholicThanks, HT.In the mountain climbing context, they both convey the meaning of 'summit'. Standing alone, 'rocky pinnacle' does not mean 'mountain top'; it could even mean 'a top business position that is hard to hold'.
I mean, does "rocky pinnacle" and "mountain pinnacle" amount to each other?