The primary issue is probably caused by the fact that FCE transcodes HD video into QuickTime/Apple Intermediate Codec during import/capture and I suspect your friend used ProRes when he/she imported clips into FCPro. If that's the case, then when you import your FCE project into FCPro, those clips are QT/AIC vs. your friend's clips being ProRes. What camcorder(s) were used to film these clips?
The render files in FCE have no bearing on importing your FCE project into FCPro. It's the source video files that are key (not the FCE project per se) ... and video captured in FCE will be transcoded to QT/AIC. While the quality of QT/AIC is quite good, depending on the original quality of your original video plus the ProRes settings used for capture in FCPro, at some point ProRes will outshine the capabilities of AIC.
The other thing is that FCE does not support 1080p material. If you succeeded in importing progressive material into FCE somehow, your results will be unpredictable. That could also be a factor.