Correct grammar is always " diferent from" and "'better than." However, in the US this is one of the most common examples of incorrect use of grammar, similar to our confustion over the proper use of words like "lie - lay", "come - go," "bring - take," "each other - one another" etc. Linguistically speaking, these errors become acceptable over time and are much more common among public speakers now than when I was young, but they are still contrary to grammatical rules.

Firstly, "different than" is just plain incorrect. Secondly, "different from" is not the only acceptable form. In fact, in the UK we would mostly regard "different from" as being bad English. Here, we instead use "different to".

Please see dancingbear and azimux's comments below, it's not Chinglish...

Never than. Chinglish reasoning. Hands down.

I agree that "different than" is dodgy grammar. We use "than" for comparatives (bigger, smaller, better, worse, more..., less..., etc) but "different" doesn't cut it because we already know there is a difference (by using "than"), so the failure is that it doesn't tell us *how* something is different to another thing. I think one's choice of using "from/to" depends on whether you consider the subject of the sentence of primary or secondary importance to something else.