A sort of alienation easy to understand is the kind that keeps people apart. A subtler sort is the kind that estranges a person from their own potential by diminishing their powers as an individual. Here is Christopher Lasch in his book The Culture of Narcissism writing on the topic:

The contemporary American may have failed, like his predecessors, to establish any sort of common life, but the integrating tendencies of modern industrial society have at the same time undermined his “isolation.” Having surrendered most of his technical skills to the corporation, he can no longer provide for his material needs. As the family loses not only its productive functions but many of its reproductive functions as well, men and women no longer manage even to raise their children without the help of certified experts. The atrophy of older traditions of self-help has eroded everyday competence, in one area after another, and has made the individual dependent on the state, the corporation, and other bureaucracies.