Difference between ZiYi and ZiXi

At my first sight of ZiXi, I thought he was just a copy of ZiYi... Then, I found there are indeed some minor differences between ZiYi and ZiXi. First of all, ZiYi has two big dimple, while ZiXi only has one at his right side of face; Second, ZiXi's nose seems to be much higher than that of ZiYi; third, ZiYi seems to have bigger eyes; fourth, ZiYi's face shape looks more like his daddy's( chubby face);fifth, ZiXi has a much smaller mouth... Many of my friends think ZiXi looks more like me.. while my hubby always believe both of his sons are just copies of himself and it is almost impossible to find a trace of my contribution by just looking at their face :) ... So, let's see

The first picture is ZiXi in his second week and the second picture is ZiYi in his second week.