Basically it is the same as a 3-0. However two things will be different: The crowd and everybody else (except the coaches) will love it for the extra action, for the amount of highlights. And, though more in theory: Let's assume two teams end up with the same amount of points at the end of the season. Then the goal difference decides. In a - theoretical - situation where one team always won 6-3, the other 2-1 the former team has the advantage as the goal difference will be better. If there are two teams who always won by the same margin (so one team always winning 6-3, one always 3-0 and the teams had a draw in the matches against each other) it could happen that both teams have the same amount of points and the same goal difference. To decide who wins the championchip the 3rd meaning is who shot more goals.

But in reality: Except for the great show a 6-3 offers, a 6-3 and a 3-0 victory are the same. Both gain 3 points, both improve the goal difference (which indeed matters at times) the same way.