/e/ is a short relaxed vowel sound. The cheeks, lips, and tongue should all be relaxed.
The/ey/ sound is longer than the /e/ sound and is tense. The mouth opens in a wide circle when saying /ey/.
Read these words to your student(s) and have them repeat.
For more pronunciation exercises, come in to pick up a copy of Pronunciation Fun! (Free for IC teachers and students.)