In the cabinet industry the word "Maple" generally refers to all of the species of Soft Maple. Hard Maple refers to one specific type of maple species: Acer saccharum. Hard Maple is also known as Rock Maple or Sugar Maple. When buying lumber we must specify Hard Maple when needed and it comes at a much higher cost that does not justify that extra hardness.
Hard Maple is only about 25% harder than Soft Maple which has the same hardness as Cherry. Soft Maple will be hard enough to be used in place of Hard Maple. Even though it is referred to as Soft Maple, it is only soft in relation to Hard Maple. In reality, the heartwood of Soft Maple can be harder than the sapwood of Hard Maple. In each load of lumber we purchase there is a mixture of sapwood and heartwood.
That extra 25% of hardness in Hard Maple begins to introduce several problems when working with it. It quickly dulls the blades and cutters. It causes problems with gluing too, the wood is so dense the glue has trouble penetrating into the pores. Problems associated with nailing and screwing, even with waxed nails and pilot holes for screws.
Hard Maple is excellent for baseball bats and bowling alleys, let's leave it there.
Refer to the links below for more reading on Hard Maple vs. Soft Maple.