Cardiovascular fitness is definitely a part of the equation, but if it were just that, it’d be “cardio”. I find that local muscular endurance tends to be the dividing line between cardio and conditioning.
Great example of this was when Mariusz Pudzianowski got into MMA. Dude was known for his conditioning in strongman, and could run circles around his opposition. He stepped in the ring and gassed within 2 rounds. Mariusz’ cardio was the same as it always was, but his conditioning for MMA was terrible, because he lacked the local specific muscular endurance (along with technique) for the sport.
You see the same thing when marathon runners go swimming, swimmers play soccer, soccer players box, etc etc. You can have some amazing cardio, but lack the conditioning for your sport.