KUN and VNO is only 1hr by car
There's of course also the excellent train from Kaunas to Vilnius centre (1:15).
But the problem is not KUN vs. VNO, it's that FR entered VNO now and competes very directly there, replicating the routes. Normally, FR would shut everybody out of the sky in such a situation. However, the good thing is that Wizz has a A320 based there, now effectively the one and only scheduled Lithuanian plane (in very sense apart from its reg) at the capital city's airport, I think people appreciate this. Wizz flies to London in the morning, while FR goes in the evening, can be nicely combined as one-ways. If MOL gets really angry though, he'll blast Wizz out of VNO with a based jet, then retreat to KUN again. My friends who use BTS say FR has basically ruined that airport. They've had EZY in the good old days, no more.