Time Spiral block had a gimmick of "timeshifted" cards.
Time Spiral had reprints of old cards, using the old frame and a purple expansion symbol (e.g.
Squire 
).
Planar Chaos had "alternative present" versions of existing cards, shifted to a different color (e.g.
Damnation 
). The frame has a different color, white text, and a textured rules text box.
Future Sight had "preprints" of potential future cards, such as those you mention. The frame is quite different, and it has a card type icon in the corner.
The special frames have no gameplay significance.
