Rear wheelbase tc02c vs evo

[Monkeysmate]

I was comparing my small fleet of tc02c against an evo at the weekend and noted that the rear wheel base was narrower on the evo.
The question I have is how? Which bit is narrower?
Are the wishbones shorter? Or is the alloy hub physically narrower than the tc02c plastic part?
I'm slowly 'evo-ing', and would like to understand the changes...
Thank you.