It looks like there's a slight difference in gearing:
4.5
Crank: Shimano R565, 50/34 (compact)
Cassette: Shimano 105 11-28, 10 speed
4.3
Crank: Shimano R565, 50/34 (compact)
Cassette: Shimano Tiagra 12-30, 10 speed
I might be wrong, but I think the 30-cog on the 4.3 is an easier gear for hills than the 28-cog on the 4.5, if that matters to you. On the other hand, my bike has an 11-28 cassette and I find it adequate for steep hills. So it might not make a difference, unless you ride in a very hilly area.
As for color, my old road bike was silver. My new road bike is also silver. I find the color of my bike to be boring. But I got a good deal on it (end of season price), which is why I bought it instead of getting a different model in another color. When I'm riding it, I am not thinking of the color, I'm just thinking that I like to ride my bike.
I actually saw the 2013 bike you're considering at the LBS the other day, and I thought the blue accents looked sharp
p.s. I think the wheels on the 2013 bike might be faster. I have Race Lite wheels, and they're noticeably faster when I'm coasting than the wheels on my old bike.
- Gray 2010 carbon WSD road bike, Rivet Independence saddle
- Red hardtail 26" aluminum mountain bike, Bontrager Evoke WSD saddle
- Royal blue 2018 aluminum gravel bike, Rivet Pearl saddle
Gone but not forgotten:
- Silver 2003 aluminum road bike
- Two awesome worn out Juliana saddles