Contacts table - Attributed to the contact(s) involved in the conversation.
Accounts table - Attributed to the account(s) involved in the conversation.
When a teammate filter is applied to the Conversations report, conversations will be counted if the teammate took any action (sent a message, commented, etc.) over the course of the conversation. The teammates selected in the filter do not need to have performed the archive action in order for the conversation to be counted toward the Archived conversations metrics in the Conversations report.
This differs from the Overview and Team Performance reports, where archive actions are attributed to the teammate who performed the archive action.