This paper helps explaining the differences between the two
Gotelli, Nicholas J., and Robert K. Colwell. 2001. “Quantifying Biodiversity: Procedures and Pitfalls in the Measurement and Comparison of Species Richness.” Ecology Letters 4 (4): 379–91.
This has already been answered on RG, have a look at this discussion instead, see: https://www.researchgate.net/post/Does_anyone_know_what_the_difference_is_between_an_accumulation_and_rarefaction_curve
Species accumulation models and pools are used to determine the richness or the number of unseen species. Accumulation curves can be derived by using raw species richness count, where these richness counts are estimated by using rarefraction curve.