Teach with Moodle

Choice, Glossary and Quizzes are about engaging your students, by interacting with your course content, rather than with other students. They are used in brainstorming activities, or a means to evaluate prior knowledge, that is prior to approaching a new topic, or after a lesson, as a means to consolidate key points.

Quizzes are extensively used as formative and summative assessment, whereas Choice is only for formative purposes.
Glossary is a simple tool used to display definitions of key words in your module. You could choose to develop this yourself, over time or ask your students to add definitions and update them (so you can use it as a tool for research/collaborative work.)

Forum discussions are about encouraging students to discuss, or share their findings with other students. By getting your students to actively search or think about an aspect of your teaching, they will remember and understand key points better. It's also about sharing new knowledge with your group.

Wiki is also collaborative but instead of only sharing you are actually asking your students to build what they need to know about an issue. So a student starts proposing an answer and another one can make changes if they spot an error (a bit like wikipedia pages).

Twitter is also about encouraging interactions between students- but outside of your module, using not only your students' knowledge and experience, but also other people outside of the module who have access to them.