Pick two funds and see how much their portfolio composition overlaps. TEFAS doesn't show this — it's derived from each fund's published holdings breakdown.
The overlap score is the sum of the smaller weight in each asset type (government bonds, reverse repo, gold, etc.) shared by both funds — the standard portfolio-overlap method. 100% means the two funds have an identical asset-type breakdown.
Limitation: this compares at the asset-type level — two funds both holding "government bonds" may hold different maturities or issues. For equity funds it does not show which individual stocks are shared, only the overall asset-class mix.