Glucose and galactose are having identical configuration in all the positions except position

Step 1: Structural Comparison — $\text{D-glucose}$ and $\text{D-galactose}$ are both aldohexoses that share identifying features across most of their structures.

Step 2: Identifying the Difference — They differ only in the configuration of the hydroxyl group on the fourth carbon ($\text{C4}$).

Step 3: Epimer Definition — Pairs like these that differ at a single chiral center are called epimers. Thus, glucose and galactose are $\text{C4 epimers}$.

Key Point: Similarly, glucose and mannose are $\text{C2 epimers}$.