mike,
the 2nd .. texturing and lighting are much better. Still a little flat looking though, you need to get a bit more dynamic range into the image. It looks like everything is being lit by ambient only with no direct light sources such as lights or sun - these will help add some contrast and liven things up a bit.
Are these both done in AC? Could be wrong but the second one seems like a different render engine .. i am not that familiar with AC rendering as anything other than shaded/hidden line images gets done in external apps
cheers,
Owen Sharp
Design Technology Manager
fjmt | francis-jones morehen thorp
iMac 27" i7 2.93Ghz | 32GB RAM | OS 10.10 | Since AC5