Many lifters will use RDLs and Good Mornings interchangeably but this study found that RDLs are more effective at targeting both the glutes and hamstrings. Both offer similar erector spinae activity, though, so use both for optimum strength development and use RDLs as a glute and hamstrings exercise staple in your program.
Reference: McAllister, M. J., Hammond, K. G., Schilling, B. K., Ferreria, L. C., Reed, J. P., & Weiss, L. W. (2014). Muscle activation during various hamstring exercises. The Journal of Strength & Conditioning Research, 28(6), 1573-1580.