Why is the Japanese Digimon Frontier different from the English Digimon Frontier?

Answer 1

It is not exclusve to Digimon, pretty much any anime suffer some changes when they are dubbed, mostly due to cultural differences between Japan and other countries. There are some things they have no problem in showing on their TV, but could induce some controversy if broadcasted in other countries like the USA, hence the differences between the japanese and english versions of Digimon Frontier.

Stuff like the amount of violence, mature themes, religious and cultural references are usually cut or severely toned down depending on the case and the company in charge of the dub.