"Corporate worship" is the term that is usually used when a large group of believers gather together for the purpose of worship. In a church setting, it would probably apply to the primary weekly worship service, which is often conducted on a Sunday morning. The "corporate" part of the expression relates to the concept of "corpus" or "corps," meaning "body."
The distinction (referring specifically to Corporate Worship, instead of just to Worship) would be between an individual's personal times of devotions or private worship and the gathering of many to worship together. It could also make a distinction between worship services of the whole church and worship events of a smaller group such as a cell group, a Bible study group, or a service group (such as a group preparing to leave to help with hurricane relief and clean-up).