EMC testing generally refers to both emissions and immunity testing. However some engineers refer to immunity testing as EMC testing and emissions testing as EMI testing.

EMC susceptibility testing can check for immunity to environmental factors such as static discharge and line transients that can occur in normal use.

As I understand,EMI is what you're putting into the environment, EMC is how vulnerable you are to the environment.

Electromagnetic Interference (EMI) is a radiated or conducted signal that is unwanted that you are trying to avoid.

You can Google "EMC vs EMI". Then you can get much more information than you will get here.