The Gemara (40a) teaches that Tana'im argue about whether the value of Kofer
is equal to the value of the Mazik (the owner of the Shor) or to the value
of the Nizak (the person who was killed). According to the opinion that
holds that Kofer is equivalent to the value of the Nizak, what difference is
there whether the owner of the Shor pays Kofer or pays compensation for the
Nizak? In either case, he is paying the same sum of money!
(a) TOSFOS (DH Mai) explains that Kofer is a more lenient payment. Since
Kofer is meant to atone for the owner of the Shor that killed, it is
comparable to a Korban, because a Korban also atones for the person who did
a sin. Just like a Korban that provides atonement (such as a Chatas) cannot
be brought after a person dies because "Ein Kaparah l'Meisim" (no atonement
can be provided for a person who is already dead), so, too, if the owner of
the Shor dies, he (his heirs) will not have to pay Kofer. However, he *will*
have to pay compensation (Damim) if the Shor killed without intent to kill.
According to Tosfos, it is not clear why the Torah should exempt the owner
from paying compensation when he pays Kofer. He (his heirs) should have to
pay after his death in order to compensate the Nizak even though it is too
late to provide atonement!
Perhaps Tosfos understood that since Kofer is a Kaparah, atonement, it is
comparable to a physical punishment, such as Misah or Galus, which also
serves to provide Kaparah, and just like a person does not have to pay for
an act for which he receives a punishment because of the rule of "Kam Lei
bid'Rabah Minei," so, too, the Chiyuv of Kofer exempts him from having to
pay compensation. (Although Tosfos on 4a, DH k'Re'i, and 26a, DH v'Yehei,
rules that "Kam Lei" does *not* exempt a person from a payment that is
related to the sin that caused the punishment, nevertheless Tosfos agrees
that according to most Tana'im one does not pay monetary compensation for
killing a person b'Mezid. See Sanhedrin 79a.)
(b) RASHI here explains that the difference between Kofer and Damim is as
follows. Since Kofer is a Kaparah, when there is a Chiyuv Kofer one must pay
Kofer in order to receive atonement. If he has no money and cannot pay
Kofer, then he will be punished at the hands of Shamayim.
It is not clear what the practical difference is, since, if a person is
penniless, there is nothing he can do about it, even if he has to pay Kofer.
The SHITAH MEKUBETZES explains that the practical difference is that he is
required to go begging until he has money to pay Kofer and receive
atonement.
Another practical difference might be, as the RA'AVAD writes, that when a
person owes money, we normally do not force him to sell his basic
necessities, whereas in order to pay Kofer perhaps he would have to sell
them in order to gain atonement.
Another practical difference according to Rashi would be in a case where a
person is uncertain whether or not he has an obligation to pay. If the
payment is simply monetary (Damim), then he will not have to pay out of
doubt, because of the rule, "ha'Motzi me'Chaveiro Alav ha'Ra'ayah." However,
if the payment that he must pay is Kofer, then, out of doubt, he will still
have to pay in order to gain atonement in case he was Chayav (as the NIMUKEI
YOSEF writes).
(c) TOSFOS suggests another answer. If the Chiyuv is because of Kofer, then
the heirs of the Nizak cannot be Mochel, they cannot forego the payment,
since the Mazik is obligated to pay in order to gain atonement for himself.
(See Tosfos in Kesuvos 29a, DH v'Al Eshes Achiv, in the name of the
Yerushalmi, and Tosfos in Kesuvos 30b, DH Zar, citing Terumos 6:1.)
How can Tosfos write that the heirs of the Nizak cannot be Mochel the Kofer?
Who will force them to take it if they are not interested in receiving it?
(If the Mazik pays them against their will, it will be a "payment against
one's will," see Insights to Gitin 75a, and see MAHARAM SHIF here.) Perhaps
Tosfos means that if the heirs are Mochel and then they change their mind,
the Mazik will have to pay Kofer, since their Mechilah does not take effect.
If the heirs refuse to take the Kofer, the Mazik will have to beg them to
take it in order for him to receive atonement.
(d) The RA'AVAD and RE'AH write that the opinion that maintains that Kofer
is the value of the Nizak does not mean that one pays the value of the Nizak
had he been an Eved. Rather, since Kofer is an atonement, one pays the value
that the Torah attributes to the Nizak, which is taken from the value of
Erchin (as mentioned in Parshas Bechukosai). However, if a person pays
Damim, he pays the value of the Nizak as an Eved. Hence, there is a
significant difference between the payment of Kofer and the payment of
Damim.
However, the RASHBA rejects this explanation based on the Gemara (42b) that
says that one pays "the full value."
(e) The BA'AL HA'ME'OR explains that the Gemara does not mean that according
to Rabah one pays Damim if the Shor kills a person. Rather, when the Beraisa
says that one pays when the Shor intended to kill one person but killed
another, it does not mean that the Shor actually killed the second person,
but that he put the second person on the verge of death. Since the Shor did
not kill the person, there is a monetary obligation for the damages, just
like in any case that the Shor damages a person, and these are the damages
to which the Gemara here refers.
This explanation creates a serious problem with understanding the Beraisa,
because our Gemara concludes that the Beraisa differentiates between when
the Shor kills a free man and when he kills an Eved. There is a Chiyuv to
pay Damim for killing a free man, but there is no Chiyuv Damim for killing
an Eved. According to the Ba'al ha'Me'or who says that killing means putting
on the verge of death, why should there be no Chiyuv to pay for damages done
to an Eved? Since the Eved did not die, the Chiyuv of Sheloshim Shekalim
does not apply, and thus one should pay for damages as usual! See the ME'IRI
who deals with this question at length.
The RAMBAN in Milchamos rejects the Ba'al ha'Me'or's explanation for this
and other reasons. He asks that the Gemara later says that a Bor that causes
the same damage as the Shor of the Beraisa does not have to pay. Why should
the owner of the Bor be Patur if the Bor did not kill the person? He should
be Chayav to pay like in every case of damages!
(The Ba'al ha'Me'or perhaps was not bothered by this question, because he
learns like Rashi on 4b, DH Tana Adam. As we explained in the Insights
there, Rashi maintains that when a Bor is deep enough to kill a person, then
the owner of the Bor is exempt for paying for damages done to a person as
well, and not just exempt for killing him.)
According to all of these answers (except for that of the Ra'avad), these
distinctions between Kofer and Damim apply even if Kofer is considered
Mamon, a monetary payment (and not Kaparah). The opinion that says that
Kofer is Mamon does not mean that Kofer does not provide atonement, because
the Torah states clearly that Kofer provides atonement ("Pidyon Nafsho,"
Shemos 21:30). Rather, it means that the atonement is acquired through
paying the compensation of Damim to the heirs of the Nizak. Hence, if the
compensation of Damim is not given, the person does not receive atonement,
and therefore he has the added obligation of Kaparah requiring him to pay
(as well as the obligation of compensation).
According to the answer of the Ra'avad, this Gemara must be following the
view that Kofer is a Kaparah, and that is why the payment is determined by
the Parshah of Erchin.