Sounds like the difference between "Mordenkainen Neutral" and the later Unaligned to me.
As I recall, Gygax used to claim Mordenkainen as True Neutral in that he had his character seeking to ever balance the scales of good and evil, law and chaos - at least outwardly. His character wasn't a reactionist, but planned his actions - when one force became too entrenched, he'd act as a counterpoint to bring things back to center, changing allegiances or taking direct action himself. In actions there was his willingness to work with the evil Sir Rolibar, his mental domination of Bigby to "reform" the wizard and other (selfish) acts that sometimes benefited one extreme or another, but always was to his own benefit.
Druidic principles for older editions were of a similar thought - neither Good nor Evil, nor Law nor Chaos had the right to hold sway - there was a time and a place for each force and allowing one to reign dominant was abhorrent to the natural cycle of the world. Too much good and natural selection cannot take place and a species/society grows weak. Too much Evil and natural selection cannot occur as everything is a target to corruption, death and animosity. Too much Law, and the world becomes stagnant and unchanging, unable to adapt and grow. Too much Chaos and there is no dependable cycle of birth, growth and death - the continuation of species is put too much at risk.
The other end of that is sort of the "survivalist" mentality of Unaligned - do whatever needs to be done in the moment to stay alive and ultimately benefit yourself (and possibly others). Acts of goodness may be performed not out of a sense of necessity or altruism, but an understanding of like often invokes like - doing good to others reflects back in similar acts performed to your benefit. An unaligned might resort to evil if they felt oppressed or jilted - an eye for an eye and perhaps then some, if one could get away with it. Same for lawful behavior - being organized, working in a group or following the laws of the land being honored and done so because it makes your own life easier. Being chaotic in independent thought, rebellion or being spurious because it suits the situation.
Personally, I posit myself in the range of Chaotic Good (with some Lawful tenancies), so my outlook may be skewed. From my point of view, there are few people or things I would classify as actively Neutral, but I can settle with the idea of a great many being Unaligned. More likely, I feel most simply aren't introspective enough to know where they might sit on D&D's alignment scale.