Any person with a SEP valid can fly any SE airplane
In addition to the SEP/SET difference, there's also the difference between land and water/amphibious. Anything that can float and fly requires an additional rating.
And in the pedantic mode: a PPL(A) with a SEP class rating is only valid on fixed wing aircraft. For rotary (helicopters) you need a PPL(H).
Wouldn't want Whirly or Whirls to feel left out of the discussion...