[rob]

I am trying to figure out whether the following compounds are enantiomers that is mirror images.
Indeed they don't look to me as enantiomers but diastereoisomers, but would like to know your opinions please. Thank you.

[alphahydroxy]

yup - you're right, they're not enantiomers...

I guess they could be called diastereoisomers, but i'd rather call them regiosomers as they are simply E (trans) and Z (cis) forms of the same molecules

[movies]

These compounds are not regioisomers.  Regioisomers correspond to compounds where a reaction has occured at one of two distinct carbon atoms.  Some professors argue that the term "regioisomer" should never be used because it is defined by a step in the mechanism and is not intrinsic to the particular molecule.

The compounds above can be called olefin isomers, stereoisomers, or diastereomers.  They can't be called identical-chiral because they are not identical.  They do have the same absolute configuration at the asymmetric carbon atom, however.

[Sigizmund]

Undoubtedly these are diastereomers. This kind of stereoisomers differs in their scalar characteristics, for example, a distance between atoms or atomic groups like in (Z)- and (E)-isomeric olefins. On the other hand - enantiomers have all scalar characteristics identical, but differ in vectorial ones like rotation DIRECTION.