AWS is not recognised as an internal or external command

I am able to execute the command aws --version in command prompt but when I try to do the same using VSTS Command Prompt task I get the above error.

Any reasons why ?

Begin by reproducing `aws --version` in a VSTS Command Prompt task and compare that environment with a normal command prompt, especially command lookup and PATH behavior. The issue does not name a source file or test, so inspect the task entry points and existing command-execution tests if available; done means the AWS command is recognized in the reported task context or the limitation is documented.

Written by the indexing model from the issue text.