Would you distinguish between a sect and a cult? If so, what distinction would you make between them?
I regard the two as separate ideas which overlap most of the time. However, I get the impression that for a lot of people they are synonyms.
In both cases, each word has more than one meaning, so I'm not sure i can really answer. However, I'll give it my best.
The most common use of the word cult refers to small, new religions outside of the mainstream that others consider to be sinister. For example, in the US where Christian culture is dominant, groups like the Hare Krishnas are looked upon as a cult.
A sect is not its own religion. It is a subgroup within a religion. It is almost the same thing as a denomination, but doesn't share the same legitimacy as a denomination. A sect is usually smaller and less organized than a denomination. It is usually seen as more marginal and contentious. Despite these subtle differences, you'll find that many people tend to use sect and denomination interchangeably. Although Branch Davidians are commonly called a cult, technically speaking they are actually a sect, a radical subgroup of Seventh Day Adventists.
Interestingly, the word cult has by far the greater stigma, but the worst religious mass suicides have actually been done by sects, such as the infamous Jonestown incident.
A well known alternative meaning of the word cult is that of a toxic religion, a group that insteading building you up tears you down. They are almost always run by a charismatic leader who exerts total control over his followers. Fear is used to keep people in line. Questions are not tolerated. People are isolated from their families and friends. Certain abuses are common, such as sexual and financial abuse. In extreme cases, families are broken up, separating spouses or children from their parents. It is in this sense that Jonestown and Branch Davidians, although they are sects, can also be called cults.
This sort of cult can be a religion, a sect, or even a single church. The destruction usually happens gradually, with trusting people slowly getting sucked into it. For example, a nice Pentecostal church can hire a new pastor who is such a gifted orator that they see him as filled with the holy spirit, not realizing that this sort of charisma is also associated with psychopathy. Without the congregation even being aware of what is happening, the new pastor slowly increases his control and intimidation. What was once a lovely, healthy church becomes a place of fear and abuse.