A collection of church vocab for writers who may not have much first hand experience with churches (by an Episcopalian):
The entryway of a church is the narthex. The place where the pews are and people sit is the nave. The (often raised) area around the alter is the sanctuary.
If a church burns incense, the metal lamp-looking thing on a chain that holds it is a thurible.
A priest or pastor (terminology varies by denomination) usually wears a plain white alb, underneath the fancier, more intricate robe called the chasuble, underneath the over-the-shoulders sash called the stole. The diamond-shaped hat worn by bishops is a mitre (pronounced my-ter) and cannot be worn by normal priests. Chasubles and stoles are often switched out for different occasions/to match the color of the liturgical/church season.
Advent is the beginning of the church year, the four Sundays leading up to Christmas, and is associated with purple (color of a king) or blue (color of the Mother Mary). Lent, on the other hand, is the 40 days leading up to Holy Week (which leads into Easter) and is associated with purple for kingship and mourning. This is the one that people may fast or give up certain things for. Both are periods of waiting but Advent is more excited while Lent is tragic. The two long periods outside set seasons or other holy days (the 12 days of Christmas, the 40 days of Easter, Pentecost, Ascension, Epiphany, etc.) I have heard called ordinary time or the green and growing season.
A denomination is a specific type or branch within Christianity. The oldest major types of Christianity are the Roman Catholics (only ones who follow the pope) and Eastern Orthodox, who broke from each other in the Great Schism of 1054. There's also the Coptic Christians, based in northern Africa I think, but I'm really unfamiliar with the history there. Protestant is an umbrella term for all the many denominations that splintered off from Catholicism during the Protestant Reformation (usually dated to Martin Luther's 95 thesis in 1517), including Lutherans, Anglicans, Episcopalians, Methodists, Pentecostals, Baptists, Calvinists, and basically any other kind you'll hear of. These tend to push for less tradition, less hierarchy (thought that can come with less oversight), and less ornateness. Non-denom is slang for a protestant church that's pretty much stand alone, and isn't part of a larger denomination or community.
A group of churches in the same denomination and the same general region may be called an archdiocese if you're Catholic, a diocese if you're Episcopalian, or a synod if you're a Lutheran. Ex: I, an Episcopalian living in western Washington State, USA, am part of the Diocese of Olympia. These areas may be brought together around a bishop and cathedral (bigger, fancier church), depending on how hierarchical the denomination is.
High-church refers to a church with more focus on traditional language, older music and customs, fancier art and decoration--a lot of the things you associate with Catholicism. Low-church is the opposite, more bare-bones and casual. As one main goal of the Protestant Reformation was to cut down on priests' egoism and corruption, generally speaking the more protestant a church is, the more low-church it will be.
Pastor tends to be the term used in more protestant circles, but meaning basically the same thing as priest. A bishop is a fancy priest with more power, an archbishop or presiding bishop is above that, and then for the Catholics you get cardinals and then the pope. A deacon (or deaconess, not sure how common that term is anymore) is a lower ordained position with less power than priest, and may be a stepping stone to priest or a calling in its own right. A layperson is any ordinary, non-ordained person serving the church in some form.
This is an over-simplification of course. feel free to correct me if i botched anything, or ask about other confusing church terms
