Eu acho que é uma pergunta difícil de responder, simplesmente porque existem muitas diferenças. Talvez eu faça o melhor para citar as próprias lembranças de Douglas Adams, feitas na introdução ao Guia do mochileiro final da galáxia , um volume de obras coletadas publicado em 1995.
Sob o título Algumas observações inúteis do autor , Douglas confidencia que -
Writing episodically meant that when I finished one episode
I had no idea about what the next one would contain. When,
in the twists and turns of the plot, some event suddenly
seemed to illuminate things that had gone before, I was as
surprised as anyone else.
Ele continua adicionando -
People I talked to seemed to like Marvin the Paranoid Android,
whom I had written in as a one-scene joke...
e em uma entrevista de rádio no site da BBC deste período ( The Doctor e Douglas ), gravado quando ele era editor de roteiro da série de TV , ele descreve com alguma franqueza como a escrita do Hitchhiker era basicamente um processo de apenas sentar na máquina de escrever tentando pensar em uma sucessão de piadas, e ocasionalmente ter um de seus personagens saindo com uma observação de uma linha ele fora de um buraco que ele cavou em.
Ele lembrou que o primeiro romance tratou apenas de parte da série de rádio original - devido a sua editora aparecer à sua porta e apreender tudo o que ele escreveu até então, depois de perder o 10º prazo (ainda assim ainda apenas novelizou os primeiros 4 scripts):
[It] was a substantially expanded version of the first four episodes of
the radio series, in which some of the characters behaved in entirely
different ways and others behaved in exactly the same ways but for
entirely different reasons, which amounts to the same thing but
saves rewriting the dialogue.
E quanto ao segundo romance:
In the fall of 1980, the second Hitchhiker book was published
in England ... It was a very substantially reworked, reedited
and contracted version of episodes 7, 8, 9, 10, 11, 12, 5 and 6
(in that order) of the radio series... [and] was called “The
Restaurant at the End of the Universe”, because it included
the material from radio episode 5 ... which was set in a
restaurant called Milliways, otherwise known as the Restaurant
at the End of the Universe.
E eis que! Houve também a influência da série de televisão:
Meanwhile, a series of six television episodes of “The Hitchhiker’s
Guide to the Galaxy” was made by the BBC and broadcast in January
1981. This was based, more or less, on the first six episodes of
the radio series. In other words, it incorporated most of the book
“The Hitchhiker’s Guide to the Galaxy” and the second half of
the book “The Restaurant at the End of the Universe”. Therefore,
though it followed the basic structure of the radio series, it
incorporated revisions from the books, which didn’t.
Mas isso foi como nada. Pois então isso aconteceu:
In the summer of 1982, a third Hitchhiker book was published
simultaneously in England and the United States, called “Life,
the Universe and Everything”. This was not based on anything that
had already been heard or seen on radio or television. In fact
it flatly contradicted episodes 7, 8, 9, 10, 11 and 12 of the
radio series. These episodes of “The Hitchhiker’s Guide to the
Galaxy,” you will remember, had already been incorporated in
revised form in the book called “The Restaurant at the End of
the Universe”.
E isso:
I wrote a fourth and last (sic) book in the trilogy, “So Long, and
Thanks for All the Fish”. This was published in Britain and
the USA in the fall of 1984 and it effectively contradicted
everything to date, up to and including itself.
Então você tem isso. Uma história lúcida e coerente se alguma vez ouvi uma. Como disse a Oolon Coluphid por alguém que se poderia esperar que soubesse melhor ...