what you can feel on a bike are the stack and reach, nothing else. comparing numbers on a chart after the fact only confirms some of the ride sensation that you feel. Coda is a performance hybrid where as Felt is more of just a commuter - shorter wheelbase means more nimble.

there is more drop to the headtube, allowing you to take on a more aerodynamic ("aggressive") posture. In fact, the reach on the Jamis is longer than the Felt by 12mm, so I presume your testride saddle height is too low.

one company's "20" will not and was never intended to match another company's "21", you cannot take a measurement somewhere on the bike that says 21". if I buy a pair of shoes 9.5 where I am from, and you buy the same in LA and we go to Europe to buy a 42-43 shoe. You'd be foolish to expect they fit EXACTLY the same, the same as a 20" bike and a 21" bike - the bigger one is NOT one inch bigger.