The Lenovo Yoga 3 Pro uses a Core M 5Y70 / 5Y71 CPU. That is a low power CPU which also has low performance; lower than a 5th gen Core i3 CPU. The integrated Intel HD 5300 is less powerful than the Intel HD 4400 found in 4th gen Intel CPUs, but more powerful than the Intel HD 4000 in 3rd gen Intel CPUs. It is considered weaker than the old nVidia GT 420m.
The Spectre X360 has the Core i5-5200u which is more powerful than the Core M CPU and the Intel HD 5500 GPU is more powerful than the Intel HD 4400; probably by 15% - 20% on average. It's performance is between the nVidia 720m and 710m, but closer to the 710m. For an integrated graphics core the Intel HD 5500 is not bad, but compared to a decent dedicated GPU it is weak.
The nVidia...