So, this is a little hard to answer. Certainly, many of the people that confessed during the trials admitted to performing witchcraft. On the other hand, it's possible that they were somehow forced into saying that.

That being said, an important thing to remember about witchcraft in New England is that it had broader ramifications to them then than it does to us now. A citizen who gave into temptation or felt vengeful toward the ministers or other citizens could be considered a witch. Given the Puritan mindset, which emphasized humanities' sinfulness and the impossibility of knowing if you are going to heaven or not, many people were constantly afraid that they had sinned and were not going to heaven. This raised the likelihood of them confessing to whatever sin that they were accused of.

The other thing, is that in the Puritan mindset in the seventeenth century, there is absolutely no distinction between natural and supernatural events. This is a little hard to understand, so I'll try and explain in more detail. If I or even one of my children gets sick, it's obviously because I have sinned somehow or the devil is testing me. Furthermore, if I see a comet, that's a portent of something. Or a famine. Or an earthquake. All of these natural events had religious meaning to the Puritans. So, following that mindset, if someone is accused of witchcraft it's because God has directed the accuser to out the witches' sin to the community. However, the Salem Witchcraft Trials took things a bit too far, and it was only afterward that people started to question whether or not they had maybe killed some innocent people in their fervor.

So, in a nutshell, the people of the time had a broader definition of witchcraft than we do. Some of the people executed probably had practiced "witchcraft" as they understood it, i.e. giving in to and/or making a deal with the devil, which might have been experienced merely as a desire to protest their current social and religious position. Whether or not they sat around a cauldron and practiced spells? Hard to say, but probably not.

Sources: Boyer and Nissenbaum, Salem Repossessed, David Hall, Worlds of Wonder, Days of Judgment, Stout, The New England Soul.