Theoretically, every implant can be loaded immediately if the implant shows a sufficient primarily stability.
In reality, immediate restoration of freshly placed implants is most useful in the aesthetic area which means front teeth (incisors, canines, premolars) – so the patient doesn't show any tooth gaps when smiling which is of particular importance if extractions need to be performed as well.
In case of posterior molar teeth, an immediate restoration does not have superior advantages thus the alternative conservative approach of restoring the implant after a healing period of several weeks is usually performed in posterior areas.