combat in the air has changed...
***the dogfight is a rare thing in modern times but still can happen...but fighter combat starts miles away!
***are there large bomber airfleets? nope precision bombing is the way in modern times!
*** tactics on land seems similar to WW2 but i think the most obvious change in tactics is in the navy! How do ships now a days look compared to the 40's. No heavy guns. No anti-aircraft guns bristling all over!...Combat at sea seems that it would be fought at a distance through missles and anti-missle defenses.! submarines attack each other with torpedoes not surface ships...subs attack surface ships with missles not torpedoes.
A modern war would be more different than similar to WW2 but there would be some things that would be similar!