HI MR.. :)
An allocation is Pareto Efficient if you move away from it one individual gets worse off and other is equally/strictly better off ie. you cannot make someone better off without making someone else worse off.
An allocation is Competitive Equilibrium allocation if that is utility maximising bundle and market clears.
ie. for Competitive equilibirum, we need to check two conditions:
(i) Given prices, Agents maximize their utility i.e find demand.
(ii) Market clears for all goods.
:)