There’s no denying the huge influence Hammett had on Philip Chandler’s work. Chandler acknowledges this in “The Art of Murder” when he wrote:

“Hammett gave murder back to the kind of people that commit it for reasons, not just to provide a corpse; and with the means at hand, not with had-wrought duelling pistols, curare an tropical fish. He took murder out of the Venetian vase and dropped it in the alley.”

Even in a paean to another writer’s style, Chandler can’t avoid using his own, unique turn of phrase.
Marlowe is a subtle evolution of Spade, rather than a straight tribute act. He contains many of his characteristics, but there are some important differences. For a start, Marlowe is smarter. He is usually (but not always) one step ahead of the bad guys. There is a scene in Falcon where Spade is held at gunpoint by Joel Cairo, who wants to search his office. (The Levantine). Spade disarms him, they talk and come to an arrangement, then as he leaves Cairo asks for his gun back. Spade obliges, and is promptly help up again, and searched. My reaction reading that scene was that Marlowe would never have fallen for that – he would have taken the bullets out of the gun. Having said that, Marlowe is not infallible – he has a particular soft spot for the good old Mickey Finn. After having been tricked by Cairo, Spade enjoys the pleasures of a traditional drugged drink scene, a favourite plot device of Chandler’s (Marlowe seems to drink a lot of drugged drinks, and seems to have a blind spot for them – the reader is screaming “no, don’t drink it you fool, it will be drugged”, but he sips away anyway, then gradually his vision fades, his speech blurs, and he falls to the ground…..). The scene in the Maltese Falcon, where Spade is drugged by the Fat Man, could easily be the archetype for that recurring nightmare.

Another difference between Spade and Marlowe is that Marlowe is significantly more pious. He is a man of high principle. Marlowe will sleep with the women he encounters in his adventures, but he won’t allow them to use their sexuality to influence him – in “The Big Sleep” for example he throws the dangerous but highly attractive Carmen Sternwood out of his apartment when she climbs uninvited into his bed. Spade has fewer scruples – he sleeps with Brigid even though he knows she is using him.

Spade is also a bully, hurting his secretary when Brigid runs away, which is in no way her fault. “I won’t be able to wear an evening gown for two weeks, you big brute.” (477) Marlowe would never bruise a woman’s shoulders, certainly not his secretary, which of course he could never afford.

Another strong echo of Chandler is the scene where Spade confronts the young man, who we later find is working for the Fat Man:
“The boy spoke two words, the first a short guttural verb, the second “you”.
“People lose teeth talking like that.” Spade’s voice was still amiable, though his face had become wooden.” (457)

In the Big Sleep there is a scene where Marlowe captures Carol Lundgren and is given the same two-word response, repeatedly, and reacts with the same dry wit.

The one thing Chandler does above all others which elevates Marlowe is giving him a voice – by using a first person, interior monologue narration, we are given an insight into Marlowe’s thoughts and feelings in a way we only peep into those of Spade’s. It is this above all else that allows us to empathise with Marlowe, to walk in his steps, even if he hides some key facts and conclusions from the reader, to keep as guessing. With Spade we only see and hear what the omniscient narrator allows us to see. This leads to explanatory scenes, where the characters’ dialogue is primarily there to help the reader “catch-up”. Marlowe is the more rounded creation, and Chandler’s narratives are the more complex and interesting, but the debt he and many other detective fiction authors owe to Hammett is unambiguous and significant.