In 73b the gemara says that kodesh has 6 stringencies and trumah just 4 and
the gemara answer:
Answer #1: There are more stringencies to Kodesh.
(k) Answer #2 Kares is more severe than death.
WHY DIDN'T THE GEMARA SIMPLY ANSWER THE SAME ANSWER (2) AT THE FORMER CASE
IN COMPARING AREL to ONEN? There is also caret in AREL?
It is not possible to say regarding the Isur of eating the Korban Pesach when one's son is an Arel that "Kares is more severe" in order to prohibit the father from eating, since there is no element of Kares at all involved with eating the Korban Pesach (first, the Gemara is referring to the father of the Arel, and second, an Arel who eats Kodshim is never punished with Kares). This reasoning is only mentioned here, on 73b, when the Gemara discusses deriving benefit from Terumah and Kodshim Teme'im by way of burning them, for eating Kodshim Teme'im has a Chumra of Kares, and therefore there is reason to be more Machmir also with deriving benefit from Kodshim Teme'im.