Just in case a few of you haven't discerned, the two products are quite different and are unrelated other than sharing a name that's almost the same. Weetabix is a British brand.

Weet-bix is made by Sanitarium and is the older of the 2 brands. Sanitarium claims to be wholly Australian-owned and is affiliated with the 7th Day Adventist church.

For whatever reason, I find the Austrlian version more filling than the British one.