Some of you guys might be wondering why yugioh Sevens is different it is because the Toei Animation Production for the yugioh changed into a different production. Also for the artwork in the other series it is pretty expensive and for a animation like this it is much cheaper. And the yugioh production works are not getting enough money so they gave up and got replace with a different company/production.
I personally like this series, not saying the other series is bad, they are pretty good. In YUGIOH Sevens duels are much quicker because they are rush duels. I personally like that. I don't want to watch 2-3 ep of players just playing cards and taking forever. This is much faster and I like it.