As with all seeming contradictions, it's the translations that's been lost. There are two words in Hebrew that is translated "man". adam, and aish, In Exo 33:11 the word "man" is aish has the meanings of friend, man, champion, one of high degree. Whereas adam in Exo 33:20 has the meaning of man, hypocrite, common sort, low degree. So no "man of low degree" - sinner, can see God's face and live. Why? Proverbs 2:22 (KJV) But the wicked shall be cut off from the earth, and the transgressors shall be rooted out of it. Psalms 37:28 (KJV) For the LORD loveth judgment, and forsaketh not his saints; they are preserved for ever: but the seed of the wicked shall be cut off. This word wicked is also translated as immoral, morally wrong, and a bad person. So, what Hebrew is saying is, a sinner cannot see God face to face and live. A righteous person can. I hope this helps.