Professor is an academic rank at universities and other post-secondary education and research institutions in most countries. Literally, professor derives from Latin as a "person who professes". Professors are usually experts in their field and teachers of the highest rank.
Albert Einstein as a professor
The Ancient Greek philosopher Socrates was one of the earliest recorded professors
Toni Morrison, Emeritus Professor at Princeton University
A chancellor is a leader of a college or university, usually either the executive or ceremonial head of the university or of a university campus within a university system.
Lord Grenville as Chancellor of the University of Oxford; painting by William Owen
The Chancellor of the University of Oxford, Lord Patten, in procession at Encaenia, 2009
William Smyth, Vice-Chancellor of the University of Oxford; painting by Gilbert Jackson