One way to read the conflict in the novel in a value-oriented way is to see Gatsby's idealism as being at odds with Tom's jaded and bigoted exceptionalism.
While Gatsby and Tom both are patently willing to destroy the marriages of others (as evidenced by their behavior), Tom is driven by a sense of entitlement closely associated with financial/material privilege while Gatsby is motivated by idealism, romance and dreams.
Tom, born into money, is seen by everyone as a cad, a brute, and a base person. These qualities appear in his dealings with Daisy, Myrtle, George Wilson and Nick as well.
Gatsby feels that his duty and his destiny are bound up in Daisy. He refuses to recognize any hurdles to winning and claiming Daisy's hand. Though he is a liar, he is dedicated to carrying his dream, his duty and his destiny. There is some honor (a strange kind, perhaps) in Gatsby.
This honor comes into conflict with Tom's selfishness, pitting Daisy as the object of struggle. Tom's sense of entitlement includes Daisy. Gatsby's idealism focuses on Daisy. One of the central conflicts of the novel grows from this intractable difference.