While Plato's Symposium consists of a series of lengthy speeches in praise of love, Xenophon's is dominated by witty repartee.
A contest of words emerges between Socrates and Callias, and each of the symposiasts is asked to describe the thing which he prides himself on most. All their answers are playful or paradoxical: Socrates, for one, prides himself on his knowledge of the art of pimping.
The story comes to a climax when Socrates praises the love Callias had for Autolycus.
However, most later scholars have taken the argument against an army of lovers in Socrates' final speech as proof that Xenophon had based his work on Plato's, since this concept is mentioned in Plato's work. The speech seems to parody or pastiche the erotic speeches in both Plato's Symposium and Phaedrus.
Though some scholars have argued that the long speech of Socrates contains later additions, and opinion is divided as to which author was first to write a Socratic symposium, a work considered the standard study of this piece as of early 2000 holds that Xenophon wrote the Symposium in the second half of the 360s, benefiting from Plato's former Socratic literature. 
As for being informative historical sources about Socrates, Xenophon's Symposium and his Oeconomicus are regarded by most scholars today as practically worthless.