<em>Glucose and galactose are monosaccharides that differ from one another only at position C-4. Thus, they are epimers that have an identical configuration in all the positions except in position C-4. ... Glucose and galactose are epimers that do not differ in position C-5 but differ in position C-4.</em>
Glucose and mannose are epimers that differ at the C-2 carbon, while glucose and galactose are epimers that differ at the C-4 carbon, as shown below. When a molecule such as glucose converts to a cyclic form, it generates a new chiral center at C-1.
