In Sun-Earth system, the distance between Lagrange points L2 and L3 is about

In the Sun-Earth system, the Lagrange points L1, L2, and L3 lie on a straight line passing through the centers of the Sun and Earth [1]. The L2 point is located approximately 1.5 million kilometers (15 lakh km) directly 'behind' the Earth as viewed from the Sun. Conversely, the L3 point is situated on the opposite side of the Sun, directly away from the Earth. Since the average distance between the Earth and the Sun is approximately 150 million kilometers (15 crore km), the L3 point is located slightly more than 1 AU from the Sun on the far side. Therefore, the total distance between L2 and L3 is roughly the sum of the Sun-Earth distance (150 million km) and the Sun-L3 distance (approx. 150 million km), plus the Earth-L2 distance (1.5 million km), totaling approximately 301.5 to 320 million kilometers, which corresponds to 32 crore kilometers.

Sources

1. [1] https://www.isro.gov.in/Assessment_spacesituation_LagrangePoint_L1.html