How does the legal definition of firing compare to the legal definition of canceling a contract? I would imagine that the outcome depends on exactly what was sp

How does the legal definition of firing compare to the legal definition of canceling a contract? I would imagine that the outcome depends on exactly what was specified in the contract itself. While I might feel sympathy for the former employees of Google, without knowing the exact conditions under which they were employed at (not by) Google, I can only sympathize and not much else.