My understanding comes from this passage in The Paccekabuddha: A Buddhist Ascetic by Ria Kloppenberg. Here is how they rank the abilities of those on the path, and those that realized the path.
The Commentary on the Khuddakapāṭha gives an exposition of the classes of living beings and classifies them from the lower to the higher stages of existence. Human beings are divided into women and men. The men those who have left their houses, the anagārika. The anāgārika are divided into ordinary people (puthujjana) and noble ones (ariya). The ariya are again classified into those who need further instruction (sekha) and those who do not need further instruction (asekha, i.e., the arahats). These are divided into those who, in their prior practise went the way of pure insight (sukkhavipassaka) and those who had started with the practise of quietude (samathayānika). The samathayānika are divided into those who have not attained the perfections of a disciple (sāvaka) and those who have.
Then follow the Paccekabuddhas, who are called higher than the disciples because of the greatness of their virtue. “Even several hundreds of disciples who are like Sāriputta
and Moggallāna do not attain a hundredth part of the virtues, of one Paccekabuddha.” Higher than the Paccekabuddhas are the Sammāsambuddhas because of the greatness of their virtue:
“For even (a group of) Paccekabuddhas seated on the whole
of the (continent of) Jambudīpa so close together that sitting
cross-legged (their knees) would touch each other, do not
attain a portion, or a sixteenth part or a small fraction (of
that) of the virtues of one perfectly enlightened one” (I 177–
(Kloppenberg,1982: pg 22-23)
My understanding from further reading about Paccekabuddhas is that the differences in enlightenment has to do with the effort, power/breadth of supernormal abilities, virtue, and teaching abilities. The virtue and teaching abilities seem to take center stage in declaring the differences between the levels. So being a Sammasambuddha would make you exceptionally gifted since you can not only realize Nibbana via your own effort, but have the abilities to teach it coherently. I’m not going to speculate on orders of magnitude though.