In your experience, what is the difference between DVD & Blu-ray DVD ?

The only difference I know so far is that Blu-ray DVD is more expensive than DVD, and so far...I don't get the chance to watch a Blu-ray DVD because I bought one last year...but it is not easy to find a Blu-ray DVD external drive (to be played on a laptop) and even if I find one, it is not cheap.

So till now, I still have no chance to watch that Blu-ray DVD that I bought.

Still, there are new DVDs that I want to buy but there are options between DVD and Blu-ray DVD.

That is why I am posting this question...get more insight from you guys who have experienced both Blu-ray and normal DVD...and is it better to get Blu-ray DVD instead of DVD even though the price is more expensive?