Rava explains the machlokes by explaining that r elazar holds hazza tzricha shiur umitzarfin lehazaos but on daf 80a rava explains r elazar as holding hazaa ein tzricha shiur and it's a knas
Yossi b, Monsey ny usa
Baruch she'Kivanta! Your question is asked by the Mesores ha'Shas here, in the margin of the Gemara in parentheses. He answers that "Rebbi Elazar" referred to here is Rebbi Elazar ben Shamu'a, while on 80a it is Rebbi Eliezer ben Horkinus. The Gemara in Yevamos 62b tells us that Rebbi Elazar ben Shamu'a was a student of Rebbi Akiva, and that is why Rabah said here in the Gemara that Rebbi Elazar is following the opinion of his teacher, Rebbi Akiva, because here the Gemara means Rebbi Elazar ben Shamu'a. The Ra'avad in Eduyos 7:5 writes that "Rebbi Elazar" cited here is without a letter "Yud" in it because it is Rebbi Elazar, while on 80a it is with a "Yud" because it is Rebbi Eliezer.
Kol Tuv,
Dovid Bloom