Yes, one of many. But the substance which is normally known simply as sugar, is sucrose. This is a dimer of glucose and fructose (i.e. it is formed when one glucose molecule and one fructose molecule react and form one sucrose molecule - and one water molecule.).
Fructose and glucose are both called monosaccarides whereas any combination of two monosaccarides is called a disaccaride.
Starch and cellulose fibers are examples of polysaccarides, i.e. compounds consisting of many small sugar units. Ultimately, they are all broken down to monosaccarides in the digestion system, provided the digestion system has the enzymes necessary. We humans can't digest cellulose, but we can digest starch.
And that's the organic chemistry lesson for today.