logically implication and tautologically implication

In Enderson's book(second edition), section 2.4, subsection
Tautologies.

In the third remark, the author says

forall x Px logically implies Pc
But forall x Px does *not* tautogically implies Pc, as `forall x Px'
and `Pc' are two different sentence symbols.

My question is, is the whole formula, namely, forall x Px or Pc,
considered as just one sentence symbol? Seems to me that a sentence
symbol is not defined in that way.

.