shimano 105 versus shamino ultegra

Is the Ultegra that much better than the 105 at smooth shifting? Getting into street riding again at a much older age, and my two choices in bikes are a Trek domane sl5 or sl6 with rim brakes. cost $2000 and $3000 I know I am getting better wheels assorted parts a lighter bike by 2.5 lbs, and the...