Maple sugar is made from the sap of the sugar maple tree. Simply put, maple sugar, it says, is bee syrup made by refining and purifying the sap of the sugar maple tree.

The process of harvesting and processing: during the day the starch stored in the roots of the maple tree is converted into twigs containing sugar and transported up the trunk, wait until the night time, the low temperature will prevent this process of transport, so people usually during the day in the spring and fall season.

For maple trees that are 30 to 40 years old, holes are drilled near the roots and tubes are inserted to get the maple sap, and a tree it can collect sap until the tree is 100 years old, and then it's boiled and refined and we end up with maple syrup.

Source

There are three types of maple trees that are commonly used to make maple sugar: the sugar maple, the red maple, and the black maple, which contain up to two-fifths of the sugar content in their sap, but the black maple is considered by some botanists to be a subspecies of the sugar maple. Because maple budding changes the flavor of maple sugar, and because red maples bud earliest of the three, their production period is shorter than the other two.

A few other species of maple are also used to make maple sugar, such as Manitoba maple, silver maple, and big-leaf maple. Birch, maple and palm trees are also used to make syrup, but this syrup is not usually called maple syrup.

Reference for the above: Baidu Encyclopedia - Maple Sugar