In Carruthers' Modern Methods of Organic Synthesis, the following aldol reactions of two (Z)-enolates with benzaldehyde are shown:
The two transition states shown seem to be different, and lead to different stereochemistry in the product (the first product has both Me and OH pointing away from the plane, whereas the second has both pointing out of the plane).
Is this significant, and if it is, how can we predict which TS is used for which problem specifically?