Indifference curves and preferences? I am going through some micro concepts and I am confused, is there a difference between deriving preferences through indifference curves and actual preferences of the consumers? 

The question I was going through was: 

Jim's utility function is $U(x; y) = xy$. Jerry's utility function is $U(x; y) = 1,000xy + 2, 000.$ Tammy's utility function is $U(x; y) = xy(1-xy)$. Oral's utility function is $-1/(10+xy)$. Billy's utility function is $U(x; y) = x/y$. Pat's utility function is $U(x; y) = -xy$.

(a) No two of these people have the same preferences.

(b) They all have the same preferences except for Billy.

(c) Jim, Jerry, and Pat all have the same indifference curves, but Jerry and Oral are the only ones with the same preferences as Jim.

(d) Jim, Tammy, and Oral all have the same preferences.

(e) There is no truth in any of the above statements.

The answer apparently is C, which implies that even though Jim, Jerry and Pat have the same indifference curves, The preferences of Pat and Jim are different, while those of Oral and Jim are the same even though they have different indifference curves. How is that possible?
A nerd loves both mathematics and physics equally, and hates sports and drinking beer equally.

A football player hates both mathematics and physics equally, and loves sports and drinking beer equally.

The nerd and the football player have the same indifference curves, but not the same preferences.

The point is this: Both agree on the "grouping" of things. But they disagree in the ranking of the groups.

Your Example

If you look at Jim and Pat, they have exactly inverse utility functions and hence inverse ranking in their preferences.

That is, if for Jim $A &gt; B = C = D &gt; E$, Pat will have $A &lt; B = C = D &lt; E$. Both agree on the three groups, but disagree on the order. Jerry's just a monotone transformation (poor Jerry).