You Do Need power plug adapter while traveling from Greece to Comoros.

Here is Why You Need An Adapter

The outlet and plug type used in Comoros are C and E and in Greece are C and F. This is how they look like.

Greece

In Greece, outlets of type C and F are in use.

Type C

Type F

Comoros

In Comoros, outlets of type C and E are in use.

Type C

Type E