The VCP5 exam may include 1 or 2 questions on CLI tools, but as PowerCLI and vSphere CLI are both valid interfaces for vSphere 5 you could potentially be asked about either or both.
PowerCLI installs on top of Windows and uses a PowerShell-like syntax. vSphere CLI is build into ESXi and also available in the vSphere Manage,ent Assistant appliance - both of those are Linux shell interfaces. There is much overlap in terms of what is possible with PowerCLI and vSphere CLI, but each also has many unique capabilities too.
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