What made Brown v. Board of Education of Topeka unique in comparison to similar cases on which the NAACP had been working to fight segregation in education? How was the argument used to fight segregation in this case a departure from the NAACP's previous legal approach?

In previous cases such as Reynolds v. Topeka (1903), the city of Topeka, Kansas, was allowed to have separate schools for black and white children. Based on the ruling in the Supreme Court case Plessy v. Ferguson (1896), facilities such as schools were allowed to be segregated as long as the schools were "equal." African American schools were, however, not equal to those of whites, as African American schools generally received less funding and were in inferior facilities. However, courts upheld the doctrine of segregation.
Brown v. Board of Education (1954) was a departure from the previous legal approach used by the National Association for the Advancement of Colored People (NAACP). Rather than trying to prove that African American schools were inferior to those of whites, the NAACP proved that segregation made African American schools inherently unequal. In other words, the simple existence of separate schools was a marker of inequality. The NAACP used psychological studies that showed that African American children had absorbed the idea that they were inferior to whites and that separate schools perpetuated this idea.
https://brownvboard.org/content/prelude-brown-1903-reynolds-v-topeka