John 6:70 70 Jesus answered them, "Did I not choose you, the Twelve? And yet one of you is a devil."
Angel - means messenger of God - i.e. one who like the Sent One, communicates everything who the Father is and what He says to others
Devil - means slanderer - one who warps the nature of God to others, that he may be worshipped
check out this attempt on the 'Slander of Judas':
- click on "Judas the Slanderer" parts 3-6