Get a hold of a good molecular modeling kit or a visualization program (there are a few good free ones online). It’s a lot easier to wrap your head around stereoisomers when you can play with the 3D representations of molecules.
View attachment 284490I literally cannot conceptualize why this is an enantiomer. They are literally the exact same thing.
No, they are not.
Even without getting a model - how can you flip them around one into another?
You cannot rotate it around horizontal axis - because this would flip the M-shaped carbon backbone into W. So the rotation which leaves the pentane backbone unchanged M would be the rotation around vertical axis.
But what happens to the hydroxyls then?
The upper form starts off having the left, say 2 hydroxyl group towards viewer and the right, then 4 hydroxyl group away from viewer.
When you flip the sheet, the 2-hydroxyl group will be on the right... but because you are now looking at it from the opposite side of sheet, it is now away from you. So you again have the left hydroxyl (now 4) towards you and the right hydroxyl away from you. The molecule is NOT converted to the form below where the left hydroxyl is away from you and right hydroxyl towards you.
Which is why they are enantiomers.