C major and E minor contrast through their respective notes C and B (in red and orange), each a half step apart or leading tones. The chords share two notes (in blue) however.
*Pythagorean comma on C = B♯+++ (Ben Johnston's notation). 531441:524288 = 23.460010 cents. Limit: 3-limit. MIDI pitch bend: 65,71 (23.461914 cents) The note de picted as lower on the staff (B♯+++) is slightly higher in pitch (than C♮).