Craft-Users

Craft-Users are individuals who are capable of wielding a "Craft", a specific supernatural power that is innate to them, and is genetic to their bloodlines. The term Seeds refers to indaviduals who have the genetic potential to awaken as a Craft-User, but have yet to do so. The term Witch is used interchangeably when referring to a Craft-User, and as a generic term to refer to anyone with the genetics connected to the Craft.

Seeds
One's craft is an inheritable genetic trait that is passed down from parent to child, the exact nature and specifics of the geneology is unclear, but it seems that it is a dormant trait that somehow become dominant through circumstances and conditions that have not been elaborate on, however some clues are offered in the series that imply that being in contact with an "Craft-User/Witch" during times of emotional insecurity or prominence could be crucial in awakenings as was the case twice in the series.

Those who posses the trait and thus likelihood of developing/awakening their craft at a later date are referred to as "Seeds", a few of whom such a Amon are employed as Witch Hunters and have made peace with eventually being hunted down themselves should it ever come to that. However it appears that at the very least the STN-J classify Seeds distinctly from Witches to an extent as they have not yet "awakened"; sense it is technically Amon who usually uses this speech pattern it could be likely that he views Seeds as innocent sense they have yet to do anything wrong with their powers themselves.

Connections to and Possible development of Anti-Social Personality Disorder
Many witches are shown in the series to be homicidal and sociopathic, disinterested in anything but self interest and survival. As it was never stated or disputed it is possible that developing such traits are connected to the awakening of one's Craft, if not caused by the awakening itself, than perhaps by the need to social distance out of fears of being treated as a pariah and hunted down by groups like Solomon. Other cases can be directly linked to causes that would cause such traits in many people and their holding of witch-genes being simply coincidental, such as extreme stress, going through tragedy without being emotionally mature enough to handle it, and social pressures in conforming to society.

Regardless of the case many Craft-Users and Witches are shown to have a tendency towards being loners not particularly keen or interested in forming genuine bonds and attachments to at the very least their co-workers. Possibly due to a desire to keep things professional given the high death count that such a dangerous job would entail.

Robin seems to be socially-inept and prefers her own company ... had remained in self-isolation for an extended period of time, things that can naturally lead to having difficulty in handling and processing one's own emotions in a healthy way. A more subtle versions of this can be seen in Kazuma Kurota's who Craft allowed him to extend his life at the cost of another's, probably atrophied his empathy on purpose out of a fear of death, yet truly loved his late wife enough to attend her funeral, thus giving the witch hunter's a clue to follow up on. Furthermore Mamoru Kudō was a young child whose grasp on right and wrong was skewed and underdeveloped at best, but his own understanding that he had killed someone does show that he might've been a homicidal monster in the body of a child.

Witches vs Craft-Users
The distinction of a Craft-User vs a Witch is largely debatable and prone to speculation as the series itself implies that the terms are used loosely in a modern sense over being the accurate definitions. Early on in the series the term "Witch" carries the negative connotation of abusing their supernatural gifts and having homicidal traits and tendencies, or at the very least commit crimes in a self-serving interest but various cases contradict this stigma. Both terms have been used to refer to specific individuals at separate or concurrent points, and some branches of Solomon do not make a distinction between the two and hunt any and all Craft-Users who have awakened to their craft as witches with extreme prejudice regardless of mental health, circumstances or having committed a crime at all.

Craft-Users appear to be a more neutral or even formal term to refer to witches whom are witch-hunters themselves or civilians who do not abuse their power, while Witch is the term to refer to a perpetrator of a crime of some sort, however this is largely a technicality, as their are no true differences between the two aside from affiliation; furthermore the word "Witch" has also been used as a generic term for known witches, craft-users and their descendants, implying that it could be the proper term for anyone with a biological connection to the Craft as a whole, or at least a convenient parlance for investigating witches, their crimes and associations.

However given real world origins and definitions of Witch and Witchcraft as a pagan religion that was often used to scapegoat political enemies of the church, it could be that witch itself is not even accurate and is merely a convenient piece of terminology that most would understand and thus associate to evil or a way to demonize and dehumanize the targets of the hunts, while a Craft-User is a more respectful term to refer to those who aid in the hunting of their fellow witch. Alternative it could be what the forebears of Solomon used to refer to Craft-Users. as Witches, regardless of it being what they called themselves or identified as as a method of propaganda, possible as a method of religious appropriation against a specific group.

Connections to the Coven
How the Coven discovered or cultivated their crafts are unknown as unlike other magical concepts in Witch Hunter Robin, they appear to be innate and unique to specific bloodlines.