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Leslie’s Power Powder PLUS is basically Cal-Hypo. See
MSDS
Leslie's Power Powder PRO is also Cal-Hyo with a slight variation in sub-ingredients. See this
MSDS
As for which one to use? If your CH level is low, you could use either to maintain your chlorine level for a while and it will also increase your CH level. But if your CH level is within range now or getting high, you should use neither of those and stick to just liquid pool chlorine (aka regular bleach) which has no CH side-effects.
Also see
ABCs of Pool Water Chemistry.