Proface vs Preface - What's the difference?

As an interjection proface

is (obsolete) much good may it do you! — a familiar salutation or welcome.

the part of the liturgy that precedes the main part of the eucharist.

(Webster 1913)

proface!

(obsolete) Much good may it do you! — a familiar salutation or welcome.

(Shakespeare)

(wikipedia preface)

* (archaic)

(en noun)

The beginning or introductory portion that comes before the main text of a document or book.

The book included a brief preface by a leading expert in the field.

An introduction, or series of preliminary remarks.

* Shakespeare

This superficial tale / Is but a preface of her worthy praise.

* Milton

Heaven's high behest no preface needs.

(Roman Catholic) The prelude or introduction to the canon of the Mass.

(prefac)

To introduce or make a comment before (the main point).

Let me preface this by saying that I don't know him that well.

To give a preface to.

to preface a book