Simply stated wikis are wikis, Lync is a messenger with advanced collaboration scenarios. Wikis help you record and keep unstructured information, while Lync is a tools for text-based and VoIP based communication, that allows you to share a presentation or screen. Conversation history can be stored, but it will not give you the reading experience of wikis and vise versa. If you are searching for Microsoft's implementation of wiki - this is SharePoint - one of the site types available in SharePoint is corporate wiki.