I'm not sure how this answers the question. Personally, I'm reasonably conversant with the ideas of relational algebra, and quite good with relational databases

I'm not sure how this answers the question. Personally, I'm reasonably conversant with the ideas of relational algebra, and quite good with relational databases. But the article at the link you suggest doesn't even contain the word "array", so I'm still no closer to understanding how this concept differs from traditional tables.