1 vs 2: Ones are much harder on themselves than twos. Twos can think highly of themselves merely by seeing themselves as considerate of others. Even when twos are self-critical, they have more of a pride in being self-critical. Twos being image-center first won't hesitate to have outbursts of emotion, which seems like a lack of self-control to the one.
1 vs 3: Ones couldn't promote themselves to save their lives while that's the three's gift should they choose to use it. Threes also have much stronger egos and are sometimes willing to cut corners. In the off-chance ones do self-promote it's for the greater good than personal benefit.
1 vs 4: A one's strict superego precludes them from emotional displays and indulging like a four. Ones unlike fours aren't reactive, they have to look before they leap before reacting emotionally. A four sees being emotional as authentic while a one sees that as a lack of self-control.
1 vs 5: Fives unlike ones don't need to adhere to standards that apply to everyone to think they are good enough. Unlike fives the way ones are rational is tied to self-control. Ones find it easy to engage the world while fives find it draining. Fives don't need to obey the rules while ones are complient to the rules.
1 vs 6: Ones unlike sixes do not worry and are very sure of themselves. They know what their purpose is in the world. They "just know" way things should be and they pride themselves in not wavering in their convictions. Ones have a drive for self-improvement that sixes don't have.
1 vs 7: Ones are inhibited. Sevens are anything but. Sevens do not believe in restricting themselves.
1 vs 8: Ones are contractive while eights are expansive. Eights are very comfortable making exceptions to the rules when judging people. Eights also find it easy to exempt themselves from following any rules. Unlike eights, ones need to follow their rules to consider themselves moral people.
1 vs 9: Ones are tight while nines are easygoing. If the one's dedication to their cause is strong enough they will view losing connection with people outside their family as necessary sacrifices for the greater good while for a nine there is nothing worse than estrangement.