Both the 8811 and 8851 operate in the same way. The 8851 adds a colored display and has USB ports for headsets.
You can learn more about the 8811 here.
You can learn more about the 8851 here.
8811/51 Phone Quick Start Guide - Knowledgebase / Phones & Conferencing / Telephones / Cisco 8800 Series - OIT Service Center
8811/51 Phone Quick Start Guide
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- Last updated: Apr 23, 2019 by Stephanie Obodda