Lectures are usually larger classes, where the lecturer introduces the core topics of a subject. Students are expected to take notes and to ask questions. If you find a lecture hard to understand, you could ask your tutor if you can record it (eg using your MP3 player) to listen to it again later.
Seminars are smaller classes, where the tutor and students discuss a previously assigned topic. Students may be asked to prepare a presentation for the discussion. Every student will need to be ready to debate the issue and to express their own opinions, even if they differ from others.
Tutorials are meetings between a tutor and an individual student or a small group of students, where you can discuss a particular piece of work or other issues related to your studies.
Practical laboratory, studio or workshop classes give you the opportunity to apply the theories you have learned. You may work individually and unsupervised, but more usually you will be part of a group and supervised.
Group work with three or four other students may be required to produce a written report, conduct a piece of research or do a presentation. This can sometimes be difficult, as students from different countries may have different views and expectations about how work will be shared and decisions made. Talk to your group members about this before you start working on your assignment.