In comparing editions of the play, one will find several relatively minor textual differences. One reason is that Sheridan revised his text repeatedly, not only prior to its first production, but afterwards.
In its earliest stages, as detailed by Thomas Moore, Sheridan developed two separate play sketches, one initially entitled "The Slanderers" that began with Lady Sneerwell and Spatter (equivalent to Snake in the final version), and the other involving the Teazles. He eventually combined these and with repeated revisions and restructuring arrived at substantially the play that we have today.
The play did not appear in an authorised edition during Sheridan's lifetime, though it was printed in Dublin in 1788 from a copy that the author had sent to his sister.
Because, as one recent editor has put it, "The School for Scandal is the most intractable problem Sheridan set his editors", editions of this play can vary considerably. For example, the Penguin Classics edition gives a text based on the 1821 edition of The Works of the Late Right Honourable Richard Brinsley Sheridan published by Murray, Ridgeway, and Wilkie, but states that it has "been emended from earlier manuscripts" and gives a detailed listing of these emendations.
The prefatory material to the Project Gutenburg text of the play acknowledges that "Current texts may usually be traced, directly or indirectly", to the 1821 edition, but presents a far different text based on a manuscript in the author's hand.
In the Project Gutenburg text's version of I.1, Lady Sneerwell's accomplice is her cousin Miss Verjuice, not the socially inferior Snake (who appears only in V.3). Here is the opening of the play as given in that text (in which the editor has retained the original spelling and punctuation of Sheridan's manuscript found at Frampton Court):
LADY SNEERWELL at her dressing table with LAPPET; MISS VERJUICE drinking chocolate
LADY SNEERWELL. The Paragraphs you say were all inserted:
VERJUICE. They were Madam—and as I copied them myself in a feigned Hand there can be no suspicion whence they came.
LADY SNEERWELL. Did you circulate the Report of Lady Brittle's Intrigue with Captain Boastall?
VERJUICE. Madam by this Time Lady Brittle is the Talk of half the Town—and I doubt not in a week the Men will toast her as a Demirep.
LADY SNEERWELL. What have you done as to the insinuation as to a certain Baronet's Lady and a certain Cook.
VERJUICE. That is in as fine a Train as your Ladyship could wish. I told the story yesterday to my own maid with directions to communicate it directly to my Hairdresser. He I am informed has a Brother who courts a Milliners' Prentice in Pallmall whose mistress has a first cousin whose sister is Feme [Femme] de Chambre to Mrs. Clackit—so that in the common course of Things it must reach Mrs. Clackit's Ears within four-and-twenty hours and then you know the Business is as good as done.
Sheridan later deleted Verjuice and gave Snake most of her lines, as reflected in the 1821 edition and those editions that follow it. Here is the opening in that text:
Lady SNEERWELL'S House.
Discovered Lady SNEERWELL at the dressing-table; SNAKE drinking chocolate.
Lady Sneer. The paragraphs, you say, Mr. Snake, were all inserted?
Snake. They were, madam; and as I copied them myself in a feigned hand, there can be no suspicion whence they came.
Lady Sneer. Did you circulate the report of Lady Brittle's intrigue with Captain Boastall?
Snake. That's in as fine a train as your ladyship could wish. In the common course of things, I think it must reach Mrs. Clackitt's ears within four and twenty hours; and then, you know, the business is as good as done.
This is a significant difference, and some editors and performers have preferred the manuscript version that includes Miss Verjuice. However, the cast list of the first production of the play in 1777 has no "Miss Verjuice" listed, showing that the change Sheridan made to combine her part with Snake's predates the premiere.
Another example of strictly verbal differences between the two texts can be found in II.1, where the Project Gutenburg text has Lady Teazle rather more pointed in suggesting that Sir Peter can oblige her by making her his "widow" (only implied by her in the 1821 text, leaving him to fill in "My widow, I suppose?" and her to add "Hem! hem!"). Also, interestingly, in Crabtree's recitation of the imaginary duel between Sir Peter and Charles Surface (V.2), the shot of Sir Peter bounces off a "little bronze Pliny" in the older version, but the bust is changed to one of "Shakspeare (sic)" in the 1821 text. Many other slight differences of a few words here and there can be found throughout the play (though these do not impact the plot the way that the deletion of Miss Verjuice does).