A lecture is delivered to a large audience, usually with little back-and-forth. A seminar is a smaller session built around discussion, often led by an expert. Picture a packed hall listening to one voice versus a table of people talking through a topic together.
The core difference
A lecture is a one-way talk to an audience; a seminar is a small, interactive discussion.
- lecture — a talk given to teach an audience about a subject: The professor's lecture on Roman history ran an hour over.
- seminar — a small class or meeting where a topic is discussed in depth, often led by an expert: The professor runs a weekly seminar on medieval history.
How to tell them apart
Size and direction of conversation are the clues. A lecture scales up to a large hall because it runs one way, speaker to audience. A seminar stays small on purpose, because its point is discussion, not delivery — everyone is expected to speak.
Lecture also has a second, unrelated meaning: a stern talking-to, as in Dad gave us a lecture about staying out too late. That sense has nothing to do with classrooms, but it is worth knowing so the word is not mistaken for seminar-style teaching when someone says they got "lectured."
