Hard Maple (AKA Hard Rock Maple) comes from the maple species Sugar
Maple. The scientific name is Acer Saccharum.

"Soft" Maple comes from some other species of maple, typically Western
Bigleaf Maple (Acer Macrophylium), Red maple (Acer Rubrum) or Silver
Maple (Acer Saccharinum).

Western Bigleaf is the source of most of the maple that has fiddleback
(flame, curly, or tiger) or quilt figure. Nice flame figure can be
found in Red Maple too. Sugar Maple occasionally has flame or quilt
figure as well, but Sugar maple is best know for Birdseye figure.

Although is is considered a soft maple, Red Maple is almost as strong,
hard and dense as sugar maple, and I've used it successfully in electric
guitar necks, which are most commonly made from Hard Rock (sugar) maple.
Western Bigleaf is significantly softer and less dense--I would not
consider using it for guitar necks.

--Steve


Ron wrote:

What the difference between the two, if there is one?

I'm looking to use some 'hard maple' for some cutting boards, but, have
noticed
that many ads mention using 'hard rock maple'.

ThankX,
Ron