Sony scd xa777es vs scd777es

Can anyone enlighten me as to the differences between these two units (other than their confusingly similar names)? Does either have balanced out? Which is considered to be the better unit? I see that one weighs almost twice as the other and is a top loader perhaps indicating better build quality. I am looking for a solid sony product as I have had good luck with my older es player.

Thanks to all
Gene