(The question we were given presumably involved comparing the differences between two editions of Dr Faustus by Christopher Marlowe.)
Structurally, the nature of the differences between the two Faustus editions are of two kinds—alterations and additions/subtractions. Loosely, the differences in text B seem to me to serve to add dramatic emphasis and simplify the moral message of the play, making F into a less-culpable pawn of good and evil rather than damned purely by his own action. The textual revisions are more thematic, seeming to me to suggest some censorship of theological terminology, as well as a subtle reinforcement of Faustus' role as a tempted bungler rather than a truly wilful guilty party.
There are a large number of obvious dramatic additions in the B-text. The showy appearances of the Good and Bad angels (V,ii) point to a more lavish production budget. Specific examples of this are the grandeur of "Music while the throne descends" and the visual presentation of hell to Faustus, a piece which calls for many extras working a stage within a stage.) In (V,i) of the B-text, beautiful Helen flies over the stage; in the A-text, she is merely brought on by Mephistopheles. These additions stir the awe the audience feels at the severity of Faustus' deeds and their consequences, because damnation comes to have simple punishment which even the most slow-witted of the audience could go home in fear of.
The graphic discovery of Faustus' limbs in the final scenes embraces the carnage to be found in "The Damnable Life", which precursed Marlowe, but is very limited given the scope of that older Faust story (the description given of Faustus' remains' discovery being "The hall lay besprinkled with blood, his brains cleaving to the wall ... In one corner lay his eyes, in another his teeth ... his head and all his joints were dashed in pieces.") This continues with the editorial sentiment of making the audience more aware of the consequences of Faustus' actions in the B-text than in the A.
The omission of the scene in which the Devils attempt to torture the Old Man in the B-text may relate to the seemingly increased freedom of those agencies to influence human endeavour. Whilst in the A-text the Old Man is visibly able to resist them through the strength of his faith, the only comparable appearance of Devils in the B-text is Lucifer, Mephistopheles and Beelzebub's appearance up on high (B,V,ii)—in which they claim the power to visit "lasting damnation".
The additions of the B-text to the last act introduce inconsistencies with the earlier text: The two editions offer some contradictory notions of damnation. In (A&B,I,iii) Mephistopheles claims "this is hell, nor am I out of it", which contrasts with the reality of physical torture emphasised in B-text, when "Hell is discovered ... [Mephistopheles saying] 'let thine eyes with horror stare into that vast perpetual torture-house'" (B,V,ii,122)
In numerous instances (for example, A,V,ii,77&112), 'God' is amended to 'heaven'. There is anecdotal historical evidence that government and church censorship took place in the period 1604 and 1616. As late as 1616, Galileo was threatened by the Inquisition for teaching the Copernican system—suggesting that taking the Lord's name in vain (or in a manner disapproved of by the church) was likely to lead to persecution. Hence the nature of some alterations may be explained away as politically motivated. However, this distinction between God and heaven may also fundamentally alter the nature of salvation; the replacement of "One drop would save my soul" in (A,V,ii,79) with "One drop ... will save me" disabuses the audience of the Calvinist notion that repentance had no impact upon one's ultimate fate: It replaces possible but unlikely leniency with Faustus' certainty of a Christ who has already sacrificed himself for mankind's sins and whose forgiveness is already guaranteed to any who would repent. Further, Faustus' conviction in his own damnation ("Damned art thou Faustus, damned, despair and die" A,V,i,48) is conspicuous by its absence from the B-text; indeed he is sure that he has yet more time to repent should he choose to do so, saying his hour is "almost come" (my italics). The Old Man's remonstrations show that this revision of damnation is not confined to Faustus' thoughts: (A,V,ii,45) "But mercy, Faustus, of thy Saviour sweet, Whose blood alone must wash away thy guilt," is replaced with the more humanist "my kind rebuke, Checking thy body, may amend thy soul" (B,V,ii,49)—the Old Man has gone directly from strict Calvinism to claiming Faustus' possible repentance as wholly his own doing!
My conclusion is that through the revisions the B-text Faustus is made not only more naive, but also more controlled in his action. Mephistopheles admits to toying with him—in B,V,ii,98 he says "'Twas I that, when thou wert i'the way to heaven, Damned up thy passage ... led thine eye") Further, the Old Man's view of Faustus' guilt subtly but radically alters—the meaning of (A,V,i,61) "thy hopeless soul" is markedly different to (B,V,i,63) "thy hapless soul", which intimates that Faustus is a bungler in matters of the spirit rather than intrinsically damned. This is probably the most important inconsistency within the two texts—though the moral message is simplified (there is left no doubt that Faustus' actions and his failure to repent have damned him), the audience may have stronger sympathies for a man who had less responsibility for those actions. The B-text Faustus attracts more sympathy because he is obviously controlled; and, as G.J.Watson states2, "It is hard to feel that justice has been done." This opens the scope of the play to a much wider (less cognitive) audience: To identify with the damned is to fear.
1. Editors footnotes p285, Marlowe, Doctor Faustus, (Manchester Uni Press, 1995)
2. G.J.Watson, Drama: An Introduction (Basingstoke: Macmillan 1983), p.47
Reference text: Marlowe, Doctor Faustus, (Manchester University Press, 1995)