Kitchen Cutting Board (Set of 3),Professional Chopping Boards Sets

What are the little pointy ridges for?

That's a non-slip mat.

Do these boards have a plastic smell?

No not at all. Recommended putting them through the dishwasher first, just for safety sake.

Difference between large and extra large on the selection?

Large size ：Large(15.6"x9.4"), Medium(12.4"x7.8"), Small(9.6"x5.7").

extra large size ：Large(16.5"x10.8"), Medium(15.6"x9.4"), Small(12.4"x7.8").

Are these boards reversible, ie, can either side be used for cutting regardless of the 'Deep Drip Groove' on one side?

Yes both sides can be used for the cutting board

Are these difficult to clean given the dark color?

Very easy to clean! I both handwash or pop in the dishwasher for a deeper cleaning.