I think I can add some useful informations in the subject of Judas death. Except of what is recorded in the New Testament, there are also other accoutns which may clear up potential consufion, remove contradictions and even propose entirely new view on the whole case of Judas death. In my opinion, they contain answer to question posted by OP: Are these two passages contradictory? How did Judas die? The answer is: no, passages are not contradictory - they just lack additional information "between". In the end Judas might have died in a way described in Acts, after he tried hanging itself but was rescued.
Let's start with quote from Papias, Apostolic Father, "hearer of John", which may initially add to general confusion about death of Judas but we will deal with it quickly:
Judas walked about in this world a sad example of impiety; for his
body having swollen to such an extent that he could not pass where a
chariot could pass easily, he was crushed by the chariot, so that his
bowels gushed out.
Quoted from: http://www.earlychristianwritings.com/text/papias.html
Now it seems, that there may be a third option for Judas death: "crushed by the chariot". Other writers tried to explain it all and clear contradictions.
Quote from Apollinarius of Laodicea, 4th century bishop of Laodicea, who is also quoting Papias (or so he says):
Judas did not die by hanging, but lived on, having been cut down
before he was suffocated. And the acts of the apostles show this,
that falling head long he burst asunder in the midst, and all his
bowels gushed out. This fact is related more clearly by Papias, the
disciple of John, and the fourth book of the Expositions of the
Oracles of the Lord as follows:
Judas walked about in this world a terrible example of impiety; his
flesh swollen to such an extent that, where hay wagon can pass with
ease, he was not able to pass, no, not even the mass of his head
merely. They say that his eyelids swelled to such an extent that he
could not see the light at all, while as for his eyes they were not
visible even by a physician looking through an instrument, so far have
they sunk from the surface.
His genitals appeared entirely disfigured, nauseous and large. When
he carried himself about discharge and worms flowed from his entire
body through his private areas only, on account of his outrages.
After many agonies and punishments, he died in his own place. And on
account of this the place is desolate and uninhabited even now. And
to this day no one is able to go by that place, except if they block
their noses with their hands. Such judgment was spread through his
body and upon the earth.
Quoted from: http://www.chronicon.net/index.php/papias
Now quote from St Ephrem:
(...) when the rope broke, he fell and burst asunder (...) others say
that Judas shut the door and barred himself in, and no one opened the
door to see what was inside until his body was decomposed and all his
bowels had gushed out
Quoted from: http://www.jstor.org/stable/3152829?seq=5
There is also very interesing quote from Theophylact (don't know which one, unfortunately):
Some say that Judas being covetous, supposed that he could both make
money by betraying Christ and yet Christ not be killed, but escape
from the Jews as he often did escape. But when he saw him now
condemned and judged to die, he repented because the affaif had turned
out other than he supposed it would. And this was why he hanged
himself in order that he might get to hades before Jesus, and there
implore him and obtain salvation. You must know however, that he
actually put his neck into the noos, having hanged himself on a
certain tree; but the tree bent down and he continued to live, because
it was God's will either to reserve him for reprentance of for open
disgrace and shame. For they say that he head the dropsy, so that he
could hardly pass where a carriage easily could pass and then he fell
on face and burst asunder.
Quote from Isho'dad, living in 9th century AD:
"He fell upon his face on the earth, and he burst asunder". They say
that when Judas hanged himself either the halter was released and he
escaped, or else someone saw him hanginng and saved him; and this
happened by providence of God, first that the disciples might not be
accused of having hanged him, and them because it ws fitting that he
who had betrayed him openly should die openly. So he lived on and saw
the resurrection of his Lord, and heard that he had come to his
disciples many times, and that he had ascended to heaven; and then he
came when many were gathered together and fell on the ground in the
midst of the city, and burst asunder"
Qoute from Dionysius Bar Salabi who also quotes Papias and Epiphanius (I don't know which one):
"He went and hanged himself." Mathew sayeth this, but Luke in the Acts
writes that he "burst in sunder" (...) and both are in the Right:
(...) for after he (...) cast a Rope about his own neck in a Wood
belonging to his House; and it happening that some passing by saw him
hanging, and loosed him before he was choked. Others say the Rope
broke, and that for some days after he was sick, and swelled to so
large dimensions as that a cart could not bear him, and his head was
sore puffed up and his eyelids so swollen that he could nod see. And
Papias saith, that his privy members were mightily enlarged, and that
putrid matter, abominable stench and Worms proceeded from them.
Epiphanius saith, That he lived four days after his Suspension and
that he was cut in twain and that his Bowels hushed out. Others [say]
that he died of that Disease, and they did not bury him, for that i
was a custom to leave those unburied who hanged themselves; Wherefore
he did stink and became offensive, and a nuisance to the Inhabitants
round about, and they were forced to remove him thence on a Bier; when
they lifted him up he fell, and bursted and all his bowels gushed out.
It is said by St. Luke in the acts of apostles, "Let his habitation be
waste": That is to say, after they had buried him, the ill savour of
his house offended the inhabitants, and they removed thence the stones
and the rest of the materials, and so his habitation became waste, to
wit, Scariot, and uninhabited. His houde was seated in Jerusalem.
Quoted from http://www.jstor.org/stable/3152829?seq=12
I do recommend for further reading: "Did Judas Really Commit Suicide?" by J. Rendel Harris