Difference between different brands of same oil I was at the supermarket just now, and there were 2 types of refined canola oil, with very different pricing. Is there any reason to believe that the cheaper one is of different quality? I mean both are oils refined from canola seeds, so I'm wondering if the pricing is only as a result of different brands.

I'm aware that for non-refined oils which are valued for taste, such as olive oil, then the answer is obvious - different olive oils give very different taste, and usually the higher the price the better the quality. As canola oil should (theoretically) be more or less tasteless, I'm wondering if this is still the case.
In practice, the major refined oils are commodity products, and the two different brands may even come from the same factory, but with different labels applied.

Still, it is possible that they are from different producers, and have a different quality standard of refining applied; one may be more aromatic than the other (which is a defect in a refined neutral oil).

The only way to know for sure is to try the less expensive brand.  If it has no off-putting aroma, you have a good value.