The enantiomers **1a** and **1b** can have their double bonds defined by [CIP rules][1] **1a** and **5**. Rule **1a** dictates that CH<sub>3</sub>>H while Rule 5 has R>S. Thus, **1a** has an *E*-double bond  and **1b** is of the *Z*-configuration as exemplified by the red bonds. [This issue has been addressed previously on this site][2].<br><br>


<img src="https://i.sstatic.net/LS5kE.jpg" height="200"><br><br>
**Addendum:** While the enantiomers **1a** and **1b** (vide supra) have their double bonds labeled in upper case E/Z ([ChemDraw][3]), [JSmol][4] takes into account the enantiomorphic nature of the double bonds by using lower case e/z (vide infra). See the answer of @orthocresol.<br><br>

<img src="https://i.sstatic.net/3pNbt.jpg" height="300">


  [1]: http://ursula.chem.yale.edu/~chem220/chem220js/STUDYAIDS/isomers/CIP%20rules%20NEW.html
  [2]: https://chemistry.stackexchange.com/questions/58630/why-is-1-ethylidene-4-methylcyclohexane-chiral/96265#96265
  [3]: https://www.perkinelmer.com/category/chemdraw
  [4]: http://jmol.sourceforge.net