Oide, K. JACoW Geneva, Switzerland 978-3-95450-187-8 10.18429/JACoW-eeFACT2016-MOOTH1 English 1-3 MOOTH1 ion dynamic-aperture sextupole collider radiation Contribution to a conference proceedings 2017 2017-07 https://doi.org/10.18429/JACoW-eeFACT2016-MOOTH1 http://jacow.org/eefact2016/papers/mooth1.pdf Designs of e⁺e⁻ colliders from the Z-pole and above are introduced. Two projects, CEPC and FCC-ee, are discussed. If we compare their schemes, a partial double ring (CEPC) and a full double ring (FCC-ee), find several important differences that affect the performance. On the other hand, there are a number of similarities in both designs, such as the crab-waist scheme, crossing angle, optimization of the dynamic aperture, etc.