The accuracy of annotation tools on a geospatial platform can vary depending on several factors, including the specific tool being used and the quality of the underlying data so this is tricky to answer
We have a few articles available online that discuss the differences but essentially RTK systems typically achieve centimeter-level accuracy in positioning X & Y, vertically having a risk of up to 0.5 datum shifts.
With GPS only it depends on various factors such as satellite geometry, signal obstructions, and atmospheric conditions. Typically, it provides meter-level accuracy under normal conditions.
The accuracy of RTK with GCPs depends on the surveying method used to establish their coordinates but typically we see around +/- 40mm