Probably a good idea to post specs pertaining to each model as each model can have various variations so people dont know which exact model you are talking about but if I have the correct variation the Envy features a i5-3337U and a HD 8750M while the Ideapad has a i5-4200U and a GT 720M.
Both have similar CPU performance, but the Envy features a much better GPU then the Ideapad (though neither GPUs are high end or even mid end, though the HD 8750M is close to mid end while the GT 720M is low level GPU).